U.S. patent application number 11/273952 was filed with the patent office on 2007-05-17 for low sulfur and low phosphorus lubricating oil composition.
This patent application is currently assigned to Chevron Oronite Company LLC. Invention is credited to Willem Van Dam.
Application Number | 20070111904 11/273952 |
Document ID | / |
Family ID | 37888205 |
Filed Date | 2007-05-17 |
United States Patent
Application |
20070111904 |
Kind Code |
A1 |
Van Dam; Willem |
May 17, 2007 |
Low sulfur and low phosphorus lubricating oil composition
Abstract
The present invention is directed to a low sulfur and low
phosphorus lubricating oil composition comprising (a) a major
amount of an oil of lubricating viscosity and (b) one or more
dispersants (c) one or more anti-oxidants and (d) one or more
detergents, wherein the lubricating oil composition is essentially
free of zinc di-alkyl di-thiophosphates and contains no more than
0.1 weight percent sulfur and provided the lubricating oil
composition does not contain alkylated and non-alkylated aromatic
amines and tri-nuclear molybdenum compounds. The present invention
is also directed to a low sulfur and low phosphorus lubricating oil
composition comprising (a) an oil of lubricating viscosity (b) a
borated dispersant and a non-borated dispersant (c) a molybdenum
anti-oxidant and a phenolic anti-oxidant and (d) a high overbased
and a low overbased calcium sulfonate, wherein the lubricating oil
composition is essentially free of zinc di-alkyl di-thiophosphates
and contains no more than 0.1 weight percent sulfur and provided
the lubricating oil composition does not contain alkylated and
non-alkylated aromatic amines and tri-nuclear molybdenum compounds.
The present invention is also directed to method for lubricating
internal combustion engines, which comprises lubricating the engine
with a low sulfur and low phosphorus lubricating oil compositions
of the present invention.
Inventors: |
Van Dam; Willem; (Novato,
CA) |
Correspondence
Address: |
CHEVRON TEXACO CORPORATION
P.O. BOX 6006
SAN RAMON
CA
94583-0806
US
|
Assignee: |
Chevron Oronite Company LLC
|
Family ID: |
37888205 |
Appl. No.: |
11/273952 |
Filed: |
November 14, 2005 |
Current U.S.
Class: |
508/273 |
Current CPC
Class: |
C10M 2207/028 20130101;
C10M 2207/026 20130101; C10N 2040/252 20200501; C10M 163/00
20130101; C10M 2219/046 20130101; C10N 2030/43 20200501; C10N
2030/42 20200501; C10N 2060/14 20130101; C10M 2215/28 20130101;
C10N 2030/40 20200501; C10M 2219/068 20130101 |
Class at
Publication: |
508/273 |
International
Class: |
C10M 135/36 20060101
C10M135/36 |
Claims
1. A low sulfur and low phosphorus lubricating oil composition
comprising: (a) a major amount of an oil of lubricating viscosity;
(b) one or more dispersants; (c) one or more anti-oxidants; and (d)
one or more detergents; wherein the lubricating oil composition is
essentially free of zinc di-alkyl di-thiophosphates and contains no
more than 0.1 weight percent sulfur and provided the lubricating
oil composition does not contain alkylated and non-alkylated
aromatic amines and tri-nuclear molybdenum compounds.
2. The lubricating oil composition of claim 1, wherein the
concentration of the zinc di-alkyl di-thiophosphates in the
lubricating oil composition is less than 0.2 weight percent based
on the total weight of the lubricating oil composition.
3. The lubricating oil composition of claim 2, wherein the
concentration of the zinc di-alkyl di-thiophosphates in the
lubricating oil composition is less than 0.1 weight percent based
on the total weight of the lubricating oil composition.
4. The lubricating oil composition of claim 3, wherein the
concentration of the zinc di-alkyl di-thiophosphates in the
lubricating oil composition is 0.0 weight percent based on the
total weight of the lubricating oil composition.
5. The lubricating oil composition of claim 1, wherein the sulfur
content is in the range of 0.0 weight percent to about 0.09 weight
percent based on the total weight of the lubricating oil
composition.
6. The lubricating oil composition of claim 5, wherein the sulfur
content is in the range of 0.01 weight percent to about 0.07 weight
percent based on the total weight of the lubricating oil
composition.
7. The lubricating oil composition of claim 6, wherein the sulfur
content is in the range of 0.02 weight percent to about 0.05 weight
percent based on the total weight of the lubricating oil
composition.
8. The lubricating oil composition of claim 1, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.03 weight percent based on the total weight of the lubricating
oil composition.
9. The lubricating oil composition of claim 8, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.02 weight percent based on the total weight of the lubricating
oil composition.
10. The lubricating oil composition of claim 9, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.01 weight percent based on the total weight of the lubricating
oil composition.
11. The lubricating oil composition of claim 10, wherein the
phosphorus content is 0.0 weight percent based on the total weight
of the lubricating oil composition.
12. The lubricating oil composition of claim 1, wherein the one or
more detergents in (d) is not an overbased metal phenate, an
overbased metal salicylate or an overbased metal carboxylate.
13. A low sulfur and low phosphorus lubricating oil composition
comprising: (a) a major amount of an oil of lubricating viscosity;
(b) a borated dispersant and a non-borated dispersant; (c) a
molybdenum-containing anti-oxidant and a phenolic anti-oxidant; and
(d) a high overbased and a low overbased calcium sulfonate; wherein
the lubricating oil composition is essentially free of zinc
di-alkyl di-thiophosphates and contains no more than 0.1 weight
percent sulfur and provided the lubricating oil composition does
not contain alkylated and non-alkylated aromatic amines and
tri-nuclear molybdenum compounds.
14. The lubricating oil composition of claim 13, wherein the
concentration of the zinc di-alkyl di-thiophosphates in the
lubricating oil composition is less than 0.2 weight percent based
on the total weight of the lubricating oil composition.
15. The lubricating oil composition of claim 14, wherein the
concentration of the zinc di-alkyl di-thiophosphates in the
lubricating oil composition is less than 0.1 weight percent based
on the total weight of the lubricating oil composition.
16. The lubricating oil composition of claim 15, wherein the
concentration of the zinc di-alkyl di-thiophosphates in the
lubricating oil composition is 0.0 weight percent based on the
total weight of the lubricating oil composition.
17. The lubricating oil composition of claim 13, wherein the sulfur
content is in the range of 0.0 weight percent to about 0.09 weight
percent based on the total weight of the lubricating oil
composition.
18. The lubricating oil composition of claim 17, wherein the sulfur
content is in the range of 0.01 weight percent to about 0.07 weight
percent based on the total weight of the lubricating oil
composition.
19. The lubricating oil composition of claim 18, wherein the sulfur
content is in the range of 0.02 weight percent to about 0.05 weight
percent based on the total weight of the lubricating oil
composition.
20. The lubricating oil composition of claim 13, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.03 weight percent based on the total weight of the lubricating
oil composition.
21. The lubricating oil composition of claim 20, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.02 weight percent based on the total weight of the lubricating
oil composition.
22. The lubricating oil composition of claim 21, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.01 weight percent based on the total weight of the lubricating
oil composition.
23. The lubricating oil composition of claim 22, wherein the
phosphorus content is 0.0 weight percent based on the total weight
of the lubricating oil composition.
24. The lubricating oil composition of claim 13, wherein the one or
more detergents in (e) is not an overbased metal phenate of, an
overbased metal salicylates or an overbased metal carboxylate.
25. A low sulfur and low phosphorus lubricating oil composition
consisting essentially of: (a) a major amount of an oil of
lubricating viscosity; (b) one or more dispersants; (c) one or more
anti-oxidants; (d) one or more detergents; and (e) one or more
additives selected from one or more viscosity index improvers,
ashless sulfur extreme pressure agents, alkaline earth metal and
alkali metal borated extreme pressure agents, molybdenum-containing
extreme pressure agents, pour point depressants, rust inhibitors,
corrosion inhibitors, ash-containing friction modifiers, ashless
friction modifiers, molybdenum-containing friction modifiers, metal
deactivators, seal swell agents, demulsifiers and anti-foaming
agents; wherein the lubricating oil composition is essentially free
of zinc di-alkyl di-thiophosphates and contains no more than 0.1
weight percent sulfur and provided the lubricating oil composition
does not contain alkylated and non-alkylated aromatic amines and
tri-nuclear molybdenum compounds.
26. The lubricating oil composition of claim 25, wherein the sulfur
content is in the range of 0.0 weight percent to about 0.09 weight
percent based on the total weight of the lubricating oil
composition.
27. The lubricating oil composition of claim 26, wherein the sulfur
content is in the range of 0.01 weight percent to about 0.07 weight
percent based on the total weight of the lubricating oil
composition.
28. The lubricating oil composition of claim 27, wherein the sulfur
content is in the range of 0.02 weight percent to about 0.05 weight
percent based on the total weight of the lubricating oil
composition.
29. The lubricating oil composition of claim 25, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.03 weight percent based on the total weight of the lubricating
oil composition.
30. The lubricating oil composition of claim 29, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.02 weight percent based on the total weight of the lubricating
oil composition.
31. The lubricating oil composition of claim 30, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.01 weight percent based on the total weight of the lubricating
oil composition.
32. The lubricating oil composition of claim 31, wherein the
phosphorus content is 0.0 weight percent based on the total weight
of the lubricating oil composition.
33. The lubricating oil composition of claim 25, wherein the one or
more detergents in (e) is not an overbased metal phenate of, an
overbased metal salicylates or an overbased metal carboxylate.
34. A low sulfur and low phosphorus lubricating oil composition
consisting essentially of: (a) a major amount of an oil of
lubricating viscosity; (b) a borated dispersant and a non-borated
dispersant; (c) a molybdenum-containing anti-oxidant and a phenolic
anti-oxidant; (d) a high overbased and a low overbased calcium
sulfonate; and (e) one or more additives selected from one or more
dispersants different from those recited in (b), anti-oxidants
different from those recited in (c), detergents different from
those recited in (d), viscosity index improvers, ashless sulfur
extreme pressure agents, alkaline earth metal and alkali metal
borated extreme pressure agents, molybdenum-containing extreme
pressure agents, pour point depressants, rust inhibitors, corrosion
inhibitors, ash-containing friction modifiers, ashless friction
modifiers, molybdenum-containing friction modifiers, metal
deactivators, seal swell agents, demulsifiers and anti-foaming
agents; wherein the lubricating oil composition is essentially free
of zinc di-alkyl di-thiophosphates and contains no more than 0.1
weight percent sulfur and provided the lubricating oil composition
does not contain alkylated and non-alkylated aromatic amines and
tri-nuclear molybdenum compounds.
35. The lubricating oil composition of claim 34, wherein the sulfur
content is in the range of 0.0 weight percent to about 0.09 weight
percent based on the total weight of the lubricating oil
composition.
36. The lubricating oil composition of claim 35, wherein the sulfur
content is in the range of 0.01 weight percent to about 0.07 weight
percent based on the total weight of the lubricating oil
composition.
37. The lubricating oil composition of claim 36, wherein the sulfur
content is in the range of 0.02 weight percent to about 0.05 weight
percent based on the total weight of the lubricating oil.
38. The lubricating oil composition of claim 34, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.03 weight percent based on the total weight of the lubricating
oil composition.
39. The lubricating oil composition of claim 38, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.02 weight percent based on the total weight of the lubricating
oil composition.
40. The lubricating oil composition of claim 39, wherein the
phosphorus content is in the range of 0.0 weight percent to about
0.01 weight percent based on the total weight of the lubricating
oil composition.
41. The lubricating oil composition of claim 40, wherein the
phosphorus content is 0.0 weight percent based on the total weight
of the lubricating oil composition.
42. The lubricating oil composition of claim 34, wherein the one or
more detergents in (e) is not an overbased metal phenate of, an
overbased metal salicylate or an overbased metal carboxylate.
43. A low sulfur and low phosphorus lubricating oil concentrate
comprising: (a) from about 10 weight percent to about 90 weight
percent an oil of lubricating viscosity based on the total weight
of the lubricating oil concentrate; (b) a borated dispersant and a
non-borated dispersant; (c) a molybdenum-containing anti-oxidant
and a phenolic anti-oxidant; and (d) a high overbased and a low
overbased calcium sulfonate; wherein the lubricating oil
concentrate is essentially free of zinc di-alkyl di-thiophosphates
and contains no more than 0.1 weight percent sulfur and provided
the lubricating oil concentrate does not contain alkylated and
non-alkylated aromatic amines and tri-nuclear molybdenum
compounds.
44. The lubricating oil concentrate of claim 43, wherein the one or
more detergents in (e) is not an overbased metal phenate of, an
overbased metal salicylate or an overbased metal carboxylate.
45. A low sulfur and low phosphorus lubricating oil concentrate
consisting essentially of: (a) from about 10 weight percent to
about 90 weight percent an oil of lubricating viscosity based on
the total weight of the lubricating oil concentrate; (b) a borated
dispersant and a non-borated dispersant; (c) a
molybdenum-containing anti-oxidant and a phenolic anti-oxidant; (d)
a high overbased and a low overbased calcium sulfonate; and (e) one
or more additives selected from one or more dispersants different
from those recited in (b), anti-oxidants different from those
recited in (c), detergents different from those recited in (d),
viscosity index improvers, ashless sulfur extreme pressure agents,
alkaline earth metal and alkali metal borated extreme pressure
agents, molybdenum-containing extreme pressure agents, pour point
depressants, rust inhibitors, corrosion inhibitors, ash-containing
friction modifiers, ashless friction modifiers,
molybdenum-containing friction modifiers, metal deactivators, seal
swell agents, demulsifiers and anti-foaming agents; wherein the
lubricating oil composition is essentially free of zinc di-alkyl
di-thiophosphates and contains no more than 0.1 weight percent
sulfur and provided the lubricating oil composition does not
contain alkylated and non-alkylated aromatic amines and tri-nuclear
molybdenum compounds.
46. The lubricating oil concentrate of claim 45, wherein the one or
more detergents in (e) is not an overbased metal phenate of, an
overbased metal salicylates or an overbased metal carboxylate.
47. A method for lubricating internal combustion engines, which
comprises lubricating the engine with a low sulfur and low
phosphorus lubricating oil composition comprising: (a) a major
amount of an oil of lubricating viscosity; (b) a borated dispersant
and a non-borated dispersant; (c) a molybdenum-containing
anti-oxidant and a phenolic anti-oxidant; and (d) a high overbased
and a low overbased calcium sulfonate; wherein the lubricating oil
composition is essentially free of zinc di-alkyl di-thiophosphates
and contains no more than 0.1 weight percent sulfur and provided
the lubricating oil composition does not contain aromatics
compounds containing amino substituents and tri-nuclear molybdenum
compounds.
48. The method of claim 47, wherein the internal combustion engines
are diesel engines, gasoline engines and natural gas engines.
49. The lubricating oil concentrate of claim 47, wherein the one or
more detergents in (e) is not an overbased metal phenate of, an
overbased metal salicylate or an overbased metal carboxylate.
50. A method for lubricating internal combustion engines, which
comprises lubricating the engine with a low sulfur and low
phosphorus lubricating oil composition consisting essentially of:
(a) a major amount of an oil of lubricating viscosity; (b) a
borated dispersant and a non-borated dispersant; (c) a
molybdenum-containing antioxidant and a phenolic anti-oxidant; (d)
a high overbased and a low overbased calcium sulfonate; and (e) one
or more additives selected from one or more dispersants different
from those recited in (b), anti-oxidants different from those
recited in (c), detergents different from those recited in (d),
viscosity index improvers, ashless sulfur extreme pressure agents,
alkaline earth metal and alkali metal borated extreme pressure
agents, molybdenum-containing extreme pressure agents, pour point
depressants, rust inhibitors, corrosion inhibitors, ash-containing
friction modifiers, ashless friction modifiers,
molybdenum-containing friction modifiers, metal deactivators, seal
swell agents, demulsifiers and anti-foaming agents; wherein the
lubricating oil composition is essentially free of zinc di-alkyl
di-thiophosphates and contains no more than 0.1 weight percent
sulfur and provided the lubricating oil composition does not
contain alkylated and non-alkylated aromatic amines and tri-nuclear
molybdenum compounds.
51. The method of claim 50, wherein the internal combustion engines
are diesel engines, gasoline engines and natural gas engines.
52. The method of claim 51, wherein the one or more detergents in
(e) is not an overbased metal phenate of, an overbased metal
salicylates or an overbased metal carboxylate.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed to a low sulfur and low
phosphorus lubricating oil composition comprising (a) a major
amount of an oil of lubricating viscosity and (b) one or more
dispersants (c) one or more anti-oxidants and (d) one or more
detergents, wherein the lubricating oil composition is essentially
free of zinc di-alkyl di-thiophosphates and contains no more than
0.1 weight percent sulfur and provided the lubricating oil
composition does not contain alkylated and non-alkylated aromatic
amines and tri-nuclear molybdenum compounds. The present invention
is also directed to a low sulfur and low phosphorus lubricating oil
composition comprising (a) an oil of lubricating viscosity (b) a
borated dispersant and a non-borated dispersant (c) a molybdenum
anti-oxidant and a phenolic anti-oxidant and (d) a high overbased
and a low overbased calcium sulfonate, wherein the lubricating oil
composition is essentially free of zinc di-alkyl di-thiophosphates
and contains no more than 0.1 weight percent sulfur and provided
the lubricating oil composition does not contain alkylated and
non-alkylated aromatic amines and tri-nuclear molybdenum compounds.
The present invention is also directed to method for lubricating
internal combustion engines, which comprises lubricating with the
low sulfur and low phosphorus lubricating oil compositions of the
present invention.
BACKGROUND OF THE INVENTION
[0002] Future diesel engines will be equipped with exhaust gas
after-treatment systems to allow them to comply with future
emission legislation. Some of these systems have proven to be
sensitive to the combustion products of the fuel and lubricant used
in the engine. Certain types of systems are sensitive to phosphorus
coming from the lubricant, others are sensitive to sulfur coming
from both fuel and lubricant, yet others are sensitive to sulfated
ash resulting from the combustion of fuel and lubricant. In order
to ensure the durability of these different types of
after-treatment systems, special lubricants are being developed
that feature low levels of sulfated ash, sulfur and phosphorus. The
most common of these lubricants provide low sulfated ash levels
with reduced sulfur and phosphorus. Less common are low or no
phosphorus lubricants that use specific, mostly sulfur or
molybdenum based, zinc di-alkyl di-thiophosphate-replacement
additives.
[0003] The guidelines for low emission diesel lubricants that will
be commercialized in 2007 and 2008 are : (1) the sulfated ash must
be equal to or lower than 1.0 weight percent for diesel engine
lubricating oils and equal to or lower than 0.5 weight percent for
passenger car diesel engine lubricating oils, (2) according to some
engine builders, sulfur content of the lubricating oil must be less
than 0.2 weight percent, while other engine builders allow up to a
maximum of 0.4 weight percent, and (3) some engine builders require
the maximum amount of phosphorus to be 0.08 weight percent, while
other engine builders allow up to 0.12 weight percent of
phosphorus. The reduction of sulfated ash closes the gap between
diesel engine lubricating oils and gasoline and natural gas engine
lubricating oils, so the use of low phosphorus, low sulfur and
sulfated ash engine lubricating oils will also be expanded to
include gasoline and natural gas engine lubricating oils.
[0004] The first generations of low emission diesel lubricating
oils were formulated to meet the above guidelines using low levels
of detergent and zinc di-alkyl di-thiophosphate. However, the
expectation is that at some point in the future, the maximum sulfur
and phosphorus content may be further reduced beyond where we
expect the industry to go between now and 2010. Lubricating oils
with no phosphorus were expected to provide no wear protection
whatsoever. In an attempt to explore the boundaries of the
performance envelope, we developed experimental lubricating oil
formulations of the present invention containing essentially no
phosphorus. Wear measurements were performed with these
experimental lubricating oils in a diesel engine and the results
showed unexpectedly low cylinder liner wear levels.
[0005] A number of patents and patent applications have discussed
methods for reducing emissions using low sulfur and low phosphorus
lubricating oil compositions, but none have disclosed a low sulfur
and low phosphorus lubricating oil composition comprising (a)
borated dispersant and anon-borated dispersant (b) a molybdenum
anti-oxidant and a phenolic anti-oxidant and (c) a low overbased
sulfonate and a high overbased sulfonate, which despite containing
essentially no zinc di-alkyl di-thiophosphate provides significant
reduction in wear.
[0006] U.S. Pat. No. 4,623,473 discloses sulfur containing
oil-soluble compositions which are useful as lubricating oil
additives, particularly in lubricants containing little or no
phosphorus. In one embodiment, the compositions of the invention
comprise (A) at least one metal salt of at least one dithiocarbamic
acid and (B) at least one oil-soluble sulfurized Diels-Alder
adduct. Such lubricating oil compositions exhibit improved
oxidation-corrosion inhibiting properties, anti-wear properties,
and/or extreme pressure properties. These lubricating oil
compositions containing less than 0.1 weight percent phosphorus
also exhibit good compatibility with nitrile seals.
[0007] U.S. Pat. No. 4,859,353 discloses sulfur-containing borate
esters for use in lubricants appropriate to modern oil requirements
with reduced or zero amounts of phosphorus and without the need for
large amounts and/or expensive forms of anti-oxidant and additional
anti-wear additives.
[0008] U.S. Pat. No. 4,990,271 discloses a lubricating oil
composition which comprises a major amount of an oil of lubricating
viscosity and a minor amount of an additive formed by contacting
molybdenum hexacarboxyl with di-xanthogens of the formula
(ROCS.sub.2).sub.2. Moreover, the lubricant compositions of this
invention do not include phosphorus.
[0009] U.S. Pat. No. 6,159,911 discloses a diesel engine oil
composition containing a lube oil base and one or more metallic
detergents-dispersants selected from among a perbasic alkaline
earth metal sulfonate, phenolate and salicylate. The total
phosphorus content of the composition is suppressed to 100 parts
per million by weight or less, to thereby provide diesel engine oil
compositions having oxidation stability and wear resistance.
[0010] U.S. Pat. No. 6,162,770 discloses an un-sulfurized, alkali
metal-free, detergent-dispersant composition having from about 40%
to 60% alkylphenol, from 10% to 40% alkaline earth alkylphenol, and
from 20% to 40% alkaline earth single aromatic-ring
alkylsalicylate. This composition may have an alkaline earth double
aromatic-ring salicylates as long as the mole ratio of single-ring
alkylsalicylate to double aromatic ring alkylsalicylate is at least
8:1.
[0011] U.S. Pat. Nos. 6,331,510 and 6,610,637 disclose a lubricant
containing (a) a synthetic base oil composition having an overall
kinematic viscosity of at least about 4.8.times.10.sup.-6 m.sup.2/s
(4.8 cSt) at 100.degree. C. and a viscosity index of at least 110;
(b) a dispersant-viscosity modifier; and (c) a sulfur-free
functionalized hydrocarbyl-substituted phenol detergent provides
improved valve train wear, with longer drain intervals, to heavy
duty diesel engines.
[0012] U.S. Pat. No. 6,376,434 discloses a lube composition which
is suitably used for diesel engines which exhaust large amounts of
sulfur dioxides. The composition exhibits corrosion/wear preventive
properties against sulfur dioxides. The lube composition includes a
lube base oil, a component (A) which is a compound selected from a
group consisting of overbased sulfonates of alkaline earth metal,
overbased phenates of alkaline earth metals and overbased
salicylates of alkaline earth metals, and a component (B) which is
a bis-type succinimide compound.
[0013] U.S. Pat. Nos. 6,408,812 and 6,588,393 disclose a low sulfur
consumable lubricating oil composition comprising a base oil, an
acylated nitrogen-containing compound having a substituent of at
least about 10 aliphatic carbon atoms; a sulfur content of about 5
to about 250 parts per million; said composition being
characterized by the absence of an extreme-pressure additive
comprised of metal and phosphorus.
[0014] U.S. Pat. No. 6,588,393 discloses a low-sulfur consumable
lubricating oil composition comprising a base oil, an acylated
nitrogen-containing compound having a substituents of at least 10
aliphatic carbon atoms, and a sulfur content of about 5 to about
250 ppm, such composition being characterized by the absence of an
extreme pressure additive comprised of metal and phosphorus.
[0015] U.S. Pat. No. 6,723,685 discloses a lubricating oil
composition comprising (a) an oil of lubricating viscosity having a
viscosity index of at least 95; (b) at least one calcium detergent;
(c) at least one oil-soluble molybdenum compound; (d) at least one
organic ashless nitro-free friction modifier; and (e) at least one
metal di-hydrocarbyl di-thiophosphate compound, the composition
having a NOACK volatility of about 15 weight percent or less, from
0.05 to 0.6 weight percent calcium from the calcium detergent,
molybdenum in an amount of at least 10 ppm from the molybdenum
compound, and phosphorus from the metal di-hydrocarbyl
di-thiophosphate compound in an amount up to about 0.1 weight
percent.
[0016] U.S. Pat. No. 6,730,638 discloses a lubricating oil for
internal combustion engines especially useful with fuels having
less than 350 parts per million sulfur comprises a lubricating oil
basestock, a boron containing ashless dispersant, a molybdenum
containing friction reduction agent, a metal type detergent and
zinc di-thiophosphate.
[0017] U.S. Pat. No. 6,777,378 discloses a lubricating oil
composition comprising: (A) a base oil; (B) a molybdenum and sulfur
containing composition derived from a basic nitrogen containing
compound, a molybdenum compound and carbon disulfide; (C) a
boron-containing compound; and (D) optionally a phosphorus
containing compound, provided the phosphorus content of the
lubricating oil composition does not exceed about 0.1 weight
percent.
[0018] U.S. Pat. No. 6,784,143 discloses the use of a minor amount
of a detergent composition comprising one or more metal detergents
which comprises metal salts of organic acids, wherein the detergent
composition comprises more than 50 mole percent, based on the moles
of the metal salts of organic acids in the detergent composition,
of: (I) a metal salt of an aromatic carboxylic acid, or (II) a
metal salt of a phenol, or (III) both a metal salt of an aromatic
carboxylic acid and a metal salt of a phenol, in a lubricating oil
composition for improving oxidation resistance of the lubricating
oil composition, wherein the amount of phosphorus and sulfur in the
oil composition is less than 0.09 mass % and at the most 0.5 mass %
respectively, based on the mass of the oil composition. It has also
been found that a detergent composition comprising more than 50
mole % of a metal salt of an aromatic carboxylic acid improves the
reduction in wear in an engine.
[0019] U.S. Pat. No. 6,852,679 discloses a lubricating oil
composition having less than 0.2 weight percent sulfur, less than
50 ppm chlorine, less than 50 ppm phosphorus, a NOACK volatility of
15 weight percent or less comprising an organo-molybdenum compound,
an overbased calcium or magnesium salicylates, a dispersant and a
supplemental anti-oxidant.
[0020] European Patent Application No. 92917678.2 (Publication No.
EP 0 556 404 A2) discloses a lubricating oil composition prepared
by compounding a base oil with a metal di-thiocarbamate and an
oil-soluble amino compound. The composition contains scarcely any
or no phosphorus and is excellent in wear resistance, extreme
pressure properties, frictional characteristics, oxidation
stability and coking resistance, thus being suitably usable as a
lubricating oil for internal combustion engines of automobiles.
[0021] European Patent Application No. 00302646.5 (Publication No.
EP 1 041 134 A1) discloses a lubricating oil composition which
contains from about 50 to 1,000, preferably 50 to 500 parts per
million of molybdenum from a molybdenum compound which is
oil-soluble and substantially free of reactive sulfur, about 1,000
to 20,000, preferably 1,000 to 10,000 parts per million of a
di-arylamine and 2,000 to 40,000 parts per million of a phenate.
This combination of ingredients provides improved oxidation control
and improved deposit control to the lubricating oil. This
composition is particularly suitable for use as a crankcase
lubricant.
[0022] European Patent Application No. 04016160.6 (Publication No.
EP 1 498 471 Al) discloses an improved lubricating oil composition
suitable for diesel engines comprising a major amount of at least
one oil of lubricating viscosity and a minor amount of an
alkylamine-alkylphosphate additive. The alkylamine-alkylphosphate
additive comprises from at least 1.25 equivalents of alkylamine to
1.0 equivalents of alkylphosphate.
[0023] U.S. patent application Ser. No. 10/344,696 (Publication No.
US 2003/0182847 A1) discloses an additive used for a fuel oil or a
lubricating oil composition for a diesel engine having a diesel
particulate filter, and a fuel oil comprising the additive. The
lubricating oil composition having a sulfated ash content of 1.0
weight percent or smaller, a sulfur content of 0.3 weight percent
or smaller and a molybdenum content of 100 ppm or greater.
[0024] U.S. patent application Ser. No. 10/277,295 (Publication No.
US 2004/0077506 A1) discloses a lubricating oil composition having
a total base number of at least about 8, comprising a major amount
of oil of lubricating viscosity; an amount of one or more
di-hydrocarbyl di-thiophosphate metal salt introducing into the
lubricating oil composition no more than 0.06 weight percent of
phosphorus; at least 1.2 weight percent of hindered phenol
antioxidant; and boron and/or boron-containing compound or
compounds in an amount providing the lubricating oil composition
wit at least 200 ppm by weight of boron, all weight percentages
being based on the total weight of the lubricating oil
composition.
[0025] U.S. patent application Ser. No. 10/649,572 (Publication No.
US 2004/0127371 A1) discloses a lubricating oil composition for use
in an internal combustion engine operated with a fuel having a
sulfur content of less than 50 ppm, that contains a minor amount of
at least one metal-containing detergent, which lubricating oil
composition, when formulated for use in a diesel engine has a total
ash content of less than 1.0 weight percent and when formulated for
use in a gasoline engine has a total ash content of less than 0.7
weight percent.
[0026] U.S. patent application Ser. No. 10/893,599 (Publication No.
US 2005/0043191 A1) discloses a substantially zinc and phosphorus
free lubricating oil meeting engine performance requirements
contains an additive system containing metal detergents, at least
one borated ashless dispersant, at least an amine anti-oxidant and
a tri-nuclear molybdenum compound. The lubricant contains a minimum
of 120 ppm boron and a minimum of 80 ppm molybdenum.
[0027] U.S. patent application Ser. No. 10/666,356 (Publication No.
US 2005/0026792 A1) discloses a lubricating oil composition with
very low phosphorus content, and having long life as evidenced by a
reduction in viscosity increase, oxidation and nitration, comprises
a major amount of a base oil of lubricating viscosity and a minor
amount of a mixer of neutral and overbased metallic detergents, at
least a zinc di-alkyl di-thiocarbamate anti-wear additive and at
least a di-hydrocarboxylthiocarbamoyl.
[0028] U.S. patent application Ser. No. 10/951,356 (Publication No.
US 2005/0137096 A1) discloses an engine lubricant that is
substantially free of zinc and phosphorus contains an anti-wear
additive comprising borated 1,2-epoxy mixed polybutenes having an
average carbon number in the range of C.sub.20 to C.sub.120.
SUMMARY OF THE INVENTION
[0029] The present invention is directed to a low sulfur and low
phosphorus lubricating oil composition comprising (a) a major
amount of an oil of lubricating viscosity and (b) one or more
dispersants (c) one or more anti-oxidants and (d) one or more
detergents, wherein the lubricating oil composition is essentially
free of zinc di-alkyl di-thiophosphates and contains no more than
0.1 weight percent sulfur and provided the lubricating oil
composition does not contain alkylated and non-alkylated aromatic
amines and tri-nuclear molybdenum compounds. The present invention
is also directed to a low sulfur and low phosphorus lubricating oil
composition comprising (a) an oil of lubricating viscosity (b) a
borated dispersant and a non-borated dispersant (c) a molybdenum
anti-oxidant and a phenolic anti-oxidant and (d) a high overbased
and a low overbased calcium sulfonate, wherein the lubricating oil
composition is essentially free of zinc di-alkyl di-thiophosphates
and contains no more than 0.1 weight percent sulfur and provided
the lubricating oil composition does not contain aromatics
alkylated and non-alkylated aromatic amines and tri-nuclear
molybdenum compounds. The present invention is also directed to
method for lubricating internal combustion engines, which comprises
lubricating the engine with a low sulfur and low phosphorus
lubricating oil compositions of the present invention.
[0030] Specifically, the present invention is directed to a low
sulfur and low phosphorus lubricating oil composition comprising:
[0031] (a) a major amount of an oil of lubricating viscosity;
[0032] (b) one or more dispersants; [0033] (c) one or more
anti-oxidants; and [0034] (d) one or more ash-containing
detergents; wherein the lubricating oil composition is essentially
free of zinc di-alkyl di-thiophosphates and contains no more than
0.1 weight percent sulfur and provided the lubricating oil
composition does not contain alkylated and non-alkylated aromatic
amines and tri-nuclear molybdenum compounds.
[0035] Preferably the one or more detergents in (d) above is not an
overbased metal phenate, an overbased metal salicylate or an
overbased metal carboxylate.
[0036] In the above lubricating oil composition of the present
invention, preferably the concentration of the zinc di-alkyl
di-thiophosphates is less than 0.2 weight percent based on the
total weight of the lubricating oil composition. More preferably
the concentration of the zinc di-alkyl di-thiophosphates is less
than 0.1 weight percent based on the total weight of the
lubricating oil composition, and most preferably the concentration
of the zinc di-alkyl di-thiophosphates is less than 0.0 based on
the total weight of the lubricating oil composition.
[0037] Preferably the lubricating oil composition of the present
invention has a low sulfated ash content.
[0038] Preferably the sulfur content of the lubricating oil
composition of the present invention is in the range of 0.0 weight
percent to about 0.09 weight percent based on the total weight of
the lubricating oil composition. More preferably the sulfur content
of the lubricating oil composition of the present invention is in
the range of 0.01 weight percent to about 0.07 weight percent based
on the total weight of the lubricating oil composition. Most
preferably the sulfur content of the lubricating oil composition of
the present invention is in the range of 0.02 weight percent to
about 0.05 weight percent based on the total weight of the
lubricating oil composition.
[0039] Preferably the phosphorus content of the lubricating oil
composition of the present invention is in the range of 0.0 weight
percent to about 0.03 weight percent based on the total weight of
the lubricating oil composition. More preferably the phosphorus
content of the lubricating oil composition of the present invention
is in the range of 0.0 weight percent to about 0.02 weight percent
based on the total weight of the lubricating oil composition. Even
more preferably the phosphorus content of the lubricating oil
composition of the present invention is in the range of 0.0 weight
percent to about 0.01 weight percent based on the total weight of
the lubricating oil composition and most preferably it is 0.0.
[0040] Preferred dispersants that may be employed in the
lubricating oil composition of the present invention are ashless
dispersants. Examples of ashless dispersants are alkenyl
succinimides and succinamides. These dispersants can be further
modified by reaction with, for example, with boron or ethylene
carbonate. Ester-based ashless dispersants derived from long chain
hydrocarbon-substituted carboxylic acids and hydroxy compounds may
also be employed. More preferred ashless dispersants are those
derived from polyisobutenyl succinic anhydride.
[0041] Preferred examples of anti-oxidants employable in the
lubricating oil of the present invention are esters of
thiodicarboxylic acids, di-thiocarbamates, such as
15-methylenebis(di-butyl di-thiocarbamate), salts of
di-thiophosphoric acids, alkyl or aryl phosphates. Molybdenum
compounds, such as amine-molybdenum complex compound and molybdenum
di-thiocarbamates may also be used as anti-oxidants and hindered
phenols, such as 4,4'-methylene-bis(2,6-di-tert-butylphenol),
4,4'-bis(2,6-di-tert-butylphenol),
4,4'-bis(2-methyl-6-tert-butylphenol),
2,2'-methylene-bis(4-methyl-6-tert-butylphenol),
4,4-butylidene-bis(3-methyl-6-tert-butylphenol),
4,4'-isopropylidene-bis(2,6-di-tert-butylphenol),
2,2'-methylene-bis(4-methyl-6-nonylphenol),
2,2'-isobutylidene-bis(4,6-dimethylphenol),
2,2'-5-methylene-bis(4-methyl-6-cyclohexylphenol),
2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol,
2,4-dimethyl-6-tert-butyl-phenol,
2,6-di-tert-1-dimethylamino-p-cresol,
2,6-di-tert-4-(N,N'-di-methylaminomethylphenol),
4,4'-thiobis(2-methyl-6-tert-butylphenol),
2,2'-thiobis(4-methyl-6-tert-butylphenol),
bis(3-methyl-4-hydroxy-5-tert-10-butylbenzyl)-sulfide, and
bis(3,5-di-tert-butyl-4-hydroxybenzyl). More preferred are hindered
phenols and molybdenum-containing compounds that do not contribute
to the phosphorus, sulfur and sulfated ash content of the
lubricating oil, provided the molybdenum compounds do not include
tri-nuclear molybdenum.
[0042] Examples of the preferred low and high overbased metal
detergents that may be employed in the lubricating oil composition
of the present invention are low and high overbased sulfonic acids
or Mannich condensation products of alkylphenols, aldehydes and
amines. More preferred are low and high overbased sulfonic acids.
It is preferred that the overbased detergents do not include
overbased salicylic acids, carboxylic acids and phenols. These
detergents may be alkali metal detergents or alkaline earth metal
detergents. Preferably they are alkaline earth metal detergents and
more preferably they are calcium detergents. The TBN of these
detergents is greater than 1 and about 500, or more.
[0043] Another embodiment of the present invention is directed to a
low sulfur and low phosphorus lubricating oil composition
comprising: [0044] (a) a major amount of an oil of lubricating
viscosity; [0045] (b) a borated dispersant and a non-borated
dispersant; [0046] (c) a molybdenum-containing anti-oxidant and a
phenolic anti-oxidants; and [0047] (d) a high overbased and a low
overbased calcium sulfonate; wherein the lubricating oil
composition is essentially free of zinc di-alkyl di-thiophosphates
and contains no more than 0.1 weight percent sulfur and provided
the lubricating oil composition does not contain alkylated and
non-alkylated aromatic amines and tri-nuclear molybdenum
compounds.
[0048] Preferably the one or more detergents in (d) above is not an
overbased metal phenate, an overbased metal salicylate or an
overbased metal carboxylate.
[0049] In the above lubricating oil composition of the above
embodiment, preferably the concentration of the zinc di-alkyl
di-thiophosphates is less than 0.2 weight percent based on the
total weight of the lubricating oil composition. More preferably
the concentration of the zinc di-alkyl di-thiophosphates is less
than 0.1 weight percent based on the total weight of the
lubricating oil composition, and most preferably the concentration
of the zinc di-alkyl di-thiophosphates is less than 0.0 based on
the total weight of the lubricating oil composition.
[0050] Preferably the sulfur content of the lubricating oil
composition of the above embodiment is in the range of 0.0 weight
percent to about 0.09 weight percent based on the total weight of
the lubricating oil composition. More preferably the sulfur content
of the lubricating oil composition of the present invention is in
the range of 0.01 weight percent to about 0.07 weight percent based
on the total weight of the lubricating oil composition. Most
preferably the sulfur content of the lubricating oil composition of
the present invention is in the range of 0.02 weight percent to
about 0.05 weight percent based on the total weight of the
lubricating oil composition.
[0051] Preferably the phosphorus content of the lubricating oil
composition of the above embodiment is in the range of 0.0 weight
percent to about 0.03 weight percent based on the total weight of
the lubricating oil composition. More preferably the phosphorus
content of the lubricating oil composition of the present invention
is in the range of 0.0 weight percent to about 0.02 weight percent
based on the total weight of the lubricating oil composition. Even
more preferably the phosphorus content of the lubricating oil
composition of the present invention is in the range of 0.0 weight
percent to about 0.01 weight percent based on the total weight of
the lubricating oil composition and most preferably it is 0.0.
[0052] Preferably the lubricating oil composition of the present
invention has low sulfated ash.
[0053] A further embodiment of the present invention is directed to
a low sulfur and low phosphorus lubricating oil composition
consisting essentially of: [0054] (a) a major amount of an oil of
lubricating viscosity; [0055] (b) one or more dispersants; [0056]
(c) one or more anti-oxidants; [0057] (d) one or more detergents;
and [0058] (e) one or more additives selected from one or more
viscosity index improvers, ashless sulfur extreme pressure agents,
alkaline earth metal and alkali metal borated extreme pressure
agents, molybdenum-containing extreme pressure agents, provided,
pour point depressants, rust inhibitors, corrosion inhibitors,
ash-containing friction modifiers, ashless friction modifiers,
molybdenum-containing friction modifiers, metal deactivators, seal
swell agents, demulsifiers and anti-foaming agents; wherein the
lubricating oil composition is essentially free of zinc di-alkyl
di-thiophosphates and contains no more than 0.1 weight percent
sulfur and provided the lubricating oil composition does not
contain alkylated and non-alkylated aromatic amines and tri-nuclear
molybdenum compounds.
[0059] Preferably the one or more detergents in (e) above is not an
overbased metal phenate, an overbased metal salicylate or an
overbased metal carboxylate.
[0060] Preferably the sulfur content of the lubricating oil
composition of the above embodiment is in the range of 0.0 weight
percent to about 0.09 weight percent based on the total weight of
the lubricating oil composition. More preferably the sulfur content
of the lubricating oil composition of the present invention is in
the range of 0.01 weight percent to about 0.07 weight percent based
on the total weight of the lubricating oil composition. Most
preferably the sulfur content of the lubricating oil composition of
the present invention is in the range of 0.02 weight percent to
about 0.05 weight percent based on the total weight of the
lubricating oil composition.
[0061] Preferably the phosphorus content of the lubricating oil
composition of the above embodiment is in the range of 0.0 weight
percent to about 0.03 weight percent based on the total weight of
the lubricating oil composition. More preferably the phosphorus
content of the lubricating oil composition of the present invention
is in the range of 0.0 weight percent to about 0.02 weight percent
based on the total weight of the lubricating oil composition. Even
more preferably the phosphorus content of the lubricating oil
composition of the present invention is in the range of 0.0 weight
percent to about 0.01 weight percent based on the total weight of
the lubricating oil composition and most preferably it is 0.0.
[0062] The lubricating oil composition of the present invention may
also contain viscosity index improvers such as olefin copolymers,
examples of which are ethylene-propylene copolymers,
styrene-isoprene copolymers, hydrated styrene-isoprene copolymers,
polybutene, polyisobutylene, polymethacrylates, vinylpyrrolidone
and methacrylate copolymers and dispersant type viscosity index
improvers.
[0063] Pour point depressants that lower the temperature at which
the fluid will flow or can be poured may also be included in the
lubricating oil composition of the present invention. Additives
that optimize the low temperature fluidity of the lubricating oil
are various copolymers, such as polymethacrylates.
[0064] The addition of rust inhibitors to the lubricating oil
composition of the present invention is also contemplated.
Preferred Rust inhibitors include nonionic polyoxyethylene surface
active agents, such as polyoxyethylene lauryl ether,
polyoxyethylene higher alcohol ether, polyoxyethylene nonyl phenyl
ether, polyoxyethylene octyl phenyl ether, polyoxyethylene octyl
stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene
sorbitol monostearate, polyoxyethylene sorbitol mono-oleate, and
polyethylene glycol mono-oleate. Other compounds that may also be
employed as rust inhibitors include stearic acid and other fatty
acids, di-carboxylic acids, metal soaps, fatty acid amine salts,
metal salts of heavy sulfonic acid, partial carboxylic acid ester
of polyhydric alcohol, and phosphoric ester. However, the more
preferred rust inhibitors are those that do not contribute to the
phosphorus or sulfur content of the lubricating oil.
[0065] Friction modifiers employable in the lubricating oil
composition of the present invention, include ash-containing as
well as ashless friction modifiers. Friction modifiers include, but
are not limited to, fatty alcohols, fatty acids, such as stearic
acid, isostearic acid, oleic acid and other fatty acids or salts
and esters thereof, borated esters, amines, phosphates, and di-,
and tri-hydrocarbyl phosphates, hydrocarbyl phosphites and
phosphonates. Friction modifiers may also contain molybdenum,
provided the molybdenum compounds do not include tri-nuclear
molybdenum. Preferably the friction modifiers used in the
lubricating oil composition of the present invention are ashless
friction modifiers.
[0066] Extreme pressure agents that may be used in the lubricating
oil composition of the present invention include alkaline earth
metal borated extreme pressure agents and alkali metal borated
extreme pressure agents. Extreme pressure agents containing
molybdenum may also be employed in the lubricating oil composition
of the present invention, provided the molybdenum compounds do not
include tri-nuclear molybdenum. Sulfurized olefins, zinc
dialky-1-dithiophosphate (primary alkyl, secondary alkyl, and aryl
type), di-phenyl sulfide, methyl tri-chlorostearate, chlorinated
naphthalene, fluoroalkylpolysiloxane, lead naphthenate, neutralized
or partially neutralized phosphates, di-thiophosphates, and
sulfur-free phosphates. The preferred extreme pressure agents are
those that will not contribute to the phosphorus content of the
lubricating oil.
[0067] Preferred corrosion inhibitors contemplated for use in the
lubricating oil of the present invention are derivatives of
di-phenyl amines, derivatives of succinimides, sulfurized olefins
and the co-sulfurized alkenyl esters/alpha olefin corrosion
inhibitors. The corrosion inhibitors such as metal
di-thiophosphates, especially zinc di-alkyl di-thiophosphate, are
less desirable because they contribute to the zinc, phosphorus and
sulfur content of the lubricating oil. More preferred corrosion
inhibitors are the derivatives of succinimides.
[0068] Metal deactivators that are employable in the lubricating
oil of the present invention include di-salicylidene
propylenediamine, triazole derivatives, mercaptobenzothiazoles,
thiodiazole derivatives, and mercaptobenzimidazoles.
[0069] The lubricating oil composition of the present invention may
employ seal swell agents, including but are not limited to,
di-esters such as di-2-ehtylhexylsebacate, di-octyladipate and
di-2-ethylhexylphthalate, mineral oils with aliphatic alcohols,
such as tri-decyl alcohol and trisphosphite ester in combination
with a hydrocarbonyl-substituted phenol.
[0070] Demulsifiers that may be employed in the lubricating oil of
the present invention include, but are not limited to, addition
product of alkylphenol and ethylene oxide, polyoxyethylene alkyl
ether, and polyoxyethylene sorbitan ester.
[0071] Useful foam inhibitors for the present invention are alkyl
methacrylate.
[0072] Another embodiment of the present invention is directed to a
low sulfur and low phosphorus lubricating oil composition
consisting essentially of: [0073] (a) a major amount of an oil of
lubricating viscosity; [0074] (b) a borated dispersant and a
non-borated dispersant; [0075] (c) a molybdenum-containing
anti-oxidant and a phenolic anti-oxidants; [0076] (d) a high
overbased and a low overbased calcium sulfonate; and [0077] (e) one
or more additives selected from one or more dispersants different
from those recited in (b), anti-oxidants different from those
recited in (c), detergents different from those recited in (d),
viscosity index improvers, ashless sulfur extreme pressure agents,
alkaline earth metal and alkali metal borated extreme pressure
agents, molybdenum-containing extreme pressure agents, pour point
depressants, rust inhibitors, corrosion inhibitors, ash-containing
friction modifiers, ashless friction modifiers,
molybdenum-containing friction modifiers, metal deactivators, seal
swell agents, demulsifiers and anti-foaming agents; wherein the
lubricating oil composition is essentially free of zinc di-alkyl
di-thiophosphates and contains no more than 0.1 weight percent
sulfur and provided the lubricating oil composition does not
contain aromatics compounds containing amino substituents and
tri-nuclear molybdenum compounds provided the lubricating oil
composition does not contain alkylated and non-alkylated aromatic
amines and tri-nuclear molybdenum compounds.
[0078] Preferably the sulfur content of the lubricating oil
composition of the above embodiment is in the range of 0.0 weight
percent to about 0.09 weight percent based on the total weight of
the lubricating oil composition. More preferably the sulfur content
of the lubricating oil composition of the present invention is in
the range of 0.01 weight percent to about 0.07 weight percent based
on the total weight of the lubricating oil composition. Most
preferably the sulfur content of the lubricating oil composition of
the present invention is in the range of 0.02 weight percent to
about 0.05 weight percent based on the total weight of the
lubricating oil composition.
[0079] Preferably the phosphorus content of the lubricating oil
composition of the above embodiment is in the range of 0.0 weight
percent to about 0.03 weight percent based on the total weight of
the lubricating oil composition. More preferably the phosphorus
content of the lubricating oil composition of the present invention
is in the range of 0.0 weight percent to about 0.02 weight percent
based on the total weight of the lubricating oil composition. Even
more preferably the phosphorus content of the lubricating oil
composition of the present invention is in the range of 0.0 weight
percent to about 0.01 weight percent based on the total weight of
the lubricating oil composition and most preferably it is 0.0.
[0080] Preferably the one or more detergents in (e) above is not an
overbased metal phenate, an overbased metal salicylate or an
overbased metal carboxylate.
[0081] In a further embodiment of the present invention, the oil of
lubricating viscosity is not a liquid polymer of alpha olefins.
[0082] Another embodiment of the present invention is directed to a
low sulfur and low phosphorus lubricating oil concentrate
comprising: [0083] (a) a major amount of an oil of lubricating
viscosity; [0084] (b) one or more dispersants; [0085] (c) one or
more anti-oxidants; and [0086] (d) one or more ash-containing
detergents; wherein the lubricating oil composition is essentially
free of zinc di-alkyl di-thiophosphates and contains no more than
0.1 weight percent sulfur and provided the lubricating oil
composition does not contain alkylated and non-alkylated aromatic
amines and tri-nuclear molybdenum compounds.
[0087] Preferably the one or more detergents in (d) above is not an
overbased metal phenate, an overbased metal salicylate or an
overbased metal carboxylate.
[0088] Another embodiment of the present invention is directed to a
low sulfur and low phosphorus lubricating oil concentrate
comprising: [0089] (a) a major amount of an oil of lubricating
viscosity; [0090] (b) a borated dispersant and a non-borated
dispersant; [0091] (c) a molybdenum-containing anti-oxidant and a
phenolic anti-oxidants; [0092] (d) a high overbased and a low
overbased calcium sulfonate; and [0093] (e) one or more additives
selected from one or more dispersants, different from those recited
in (b), anti-oxidants different from those recited in (c),
detergents different from those recited in (d), viscosity index
improvers, ashless sulfur extreme pressure agents, alkaline earth
metal and alkali metal borated extreme pressure agents,
molybdenum-containing extreme pressure agents, pour point
depressants, rust inhibitors, corrosion inhibitors, ash-containing
friction modifiers, ashless friction modifiers,
molybdenum-containing friction modifiers, metal deactivators, seal
swell agents, demulsifiers and anti-foaming agents; wherein the
lubricating oil composition is essentially free of zinc di-alkyl
di-thiophosphates and contains no more than 0.1 weight percent
sulfur and provided the lubricating oil composition does not
contain alkylated and non-alkylated aromatic amines and tri-nuclear
molybdenum compounds.
[0094] Preferably the one or more detergents in (e) above is not an
overbased metal phenate, an overbased metal salicylate or an
overbased metal carboxylate.
[0095] A further embodiment of the present invention is directed to
a method for lubricating internal combustion engines, which
comprises lubricating the engine with a low sulfur and low
phosphorus lubricating oil composition comprising: [0096] (a) a
major amount of an oil of lubricating viscosity; [0097] (b) one or
more dispersants; [0098] (c) one or more anti-oxidants; and [0099]
(d) one or more ash-containing detergents; wherein the lubricating
oil composition is essentially free of zinc di-alkyl
di-thiophosphates and contains no more than 0.1 weight percent
sulfur and provided the lubricating oil composition does not
contain alkylated and non-alkylated aromatic amines and tri-nuclear
molybdenum compounds.
[0100] In the above a method for lubricating internal combustion
engines the engines are diesel engines, gasoline engines and
natural gas engines.
[0101] Preferably the one or more detergents in (d) above is not an
overbased metal phenate, an overbased metal salicylate or an
overbased metal carboxylate.
[0102] Another embodiment of the present invention is directed to a
method for lubricating internal combustion engines, which comprises
lubricating the engine with a low sulfur and low phosphorus
lubricating oil composition consisting essentially of: [0103] (a) a
major amount of an oil of lubricating viscosity; [0104] (b) a
borated dispersant and a non-borated dispersant; [0105] (c) a
molybdenum-containing anti-oxidant and a phenolic anti-oxidants;
[0106] (d) a high overbased and a low overbased calcium sulfonate;
and [0107] (e) one or more additives selected from one or more
dispersants different from those recited in (b), anti-oxidants
different from those recited in (c), detergents different from
those recited in (d), viscosity index improvers, ashless sulfur
extreme pressure agents, alkaline earth metal and alkali metal
borated extreme pressure agents, molybdenum-containing extreme
pressure agents, pour point depressants, rust inhibitors, corrosion
inhibitors, ash-containing friction modifiers, ashless friction
modifiers, molybdenum-containing friction modifiers, metal
deactivators, seal swell agents, demulsifiers and anti-foaming
agents; wherein the lubricating oil composition is essentially free
of zinc di-alkyl di-thiophosphates and contains no more than 0.1
weight percent sulfur and provided the lubricating oil composition
does not contain alkylated and non-alkylated aromatic amines and
tri-nuclear molybdenum compounds.
[0108] In the above a method for lubricating internal combustion
engines the engines are diesel engines, gasoline engines and
natural gas engines.
[0109] Preferably the one or more detergents in (e) above is not an
overbased metal phenate, an overbased metal salicylate or an
overbased metal carboxylate.
DETAILED DISCRIPTION OF THE INVENTION
Definitions
[0110] As used herein, the following terms have the following
meanings unless expressly stated to the contrary:
[0111] The term "alkali metal" as used herein refers to Group IA
metals of the Periodic Table.
[0112] The term "alkaline earth metal" as used herein refers to
Group II metals of the Periodic Table, such as calcium and
magnesium.
[0113] The term "essentially free" as used herein refers to the
zinc di-alkyl di-thiophosphate content in the lubricating oil
composition of the present invention. Preferably zinc di-alkyl
di-thiophosphate content in the lubricating oil composition is less
than 0.2 weight percent based on the total weight of the
lubricating oil composition. More preferably the zinc di-alkyl
di-thiophosphate content in the lubricating oil composition is less
than 0.1 weight percent based on the total weight of the
lubricating oil composition. Even more preferably the zinc di-alkyl
di-thiophosphate content in the lubricating oil composition is less
than 0.05 weight percent based on the total weight of the
lubricating oil composition. Most preferably the zinc di-alkyl
di-thiophosphate content in the lubricating oil composition is 0.0
weight percent based on the total weight of the lubricating oil
composition.
[0114] The term "low phosphorus" as used herein refers to the
phosphorus content of the lubricating oil. The phosphorus content
of the lubricating oil is preferably in the range from about 0.0
weight percent to about 0.03 weight percent based on the total
weight of the lubricating oil. More preferably the phosphorus
content of the lubricating oil is in the range from about 0.0
weight percent to about 0.02 weight percent based on the total
weight of the lubricating oil. Even more preferably the phosphorus
content of the lubricating oil is in the range from about 0.0
weight percent to about 0.01 weight percent based on the total
weight of the lubricating oil. Most preferably the phosphorus
content of the lubricating oil is 0.0 weight percent based on the
total weight of the lubricating oil.
[0115] The term "low sulfur" as used herein refers to the sulfur
content of the lubricating oil. The sulfur content of the
lubricating oil is no more than 0.1 weight percent based on the
total weight of the lubricating oil composition. Preferably the
sulfur content is in the range from about 0.0 weight percent to
about 0.09 weight percent based on the total weight of the
lubricating oil. More preferably the sulfur content of the
lubricating oil is in the range from about 0.0 weight percent to
about 0.07 weight percent based on the total weight of the
lubricating oil. Most preferably the sulfur content of the
lubricating oil is preferably in the range from about 0.0 weight
percent to about 0.05 weight percent based on the total weight of
the lubricating oil.
[0116] The term "overbased" as used herein refers to alkali metal
and alkaline earth metal alkyl sulfonates in which the ratio of the
number of equivalents of an alkali metal or alkaline earth metal to
the number of equivalents of the organic moiety is greater than 1.
Low overbased refers to alkali metal or alkaline earth metal alkyl
sulfonates having a Total Base Number (TBN) greater than 1 and less
than 20, medium overbased refers to alkali metal or alkaline earth
metal alkyl sulfonates having a TBN greater than 20 and less than
200. High overbased refers to alkali metal or alkaline earth metal
alkyl sulfonates having a TBN greater than 200.
[0117] The term "sulfated ash" as used herein refers to the
non-combustible residue resulting from detergents and metallic
additives in lubricating oil. Sulfated ash may be determined using
ASTM Test D874.
[0118] The term "Total Base Number" or "TBN" as used herein refers
to the amount of base equivalent to milligrams of KOH in one gram
of sample. Thus, higher TBN numbers reflect more alkaline products,
and therefore a greater alkalinity. TBN was determined using ASTM D
2896 test.
[0119] Unless otherwise specified, all percentages are in weight
percent.
Lubricating Oil Composition
[0120] It has been discovered that the a low sulfur and low
phosphorus lubricating oil composition of the present invention
provides good wear control when used in diesel engines, gasoline
engines and natural gas engines. Wear control in conventional
lubricating oil compositions is achieved by the addition of metal
salts of di-alkyl di-thiophosphates, for example zinc di-alkyl
di-thiophosphates, however, the phosphorus causes inactivation of
oxidation catalysts used in exhaust after-treatment devices. The
lubrication oil composition of the present invention provides good
wear control without contributing to high sulfur content, and
because it contains essentially no phosphorus, it does not
inactivate the oxidation catalysts. The lubricating oil formulation
of the present invention featuring ultra-low or no phosphorus in
combination with low sulfur and sulfated ash exhibited excellent
cylinder liner wear control.
[0121] The lubricating oil composition of the present invention may
be prepared by simple blending or mixing of the compounds described
in more detail below. These compounds may also be preblended as a
concentrate or package with various other additives in appropriate
ratios to facilitate blending of a lubricating oil composition
containing the desired concentration of additives.
[0122] Oil of Lubricating Viscosity
[0123] Oil of lubricating viscosity, or base oil as used herein
refer to lubricating oils which may be mineral oil or synthetic
oils of lubricating viscosity and preferably useful in the
crankcase of an internal combustion engine. Crankcase lubricating
oils ordinarily have a viscosity of about 1300 centistokes at
-17.8.degree. C. to 22.7 centistokes at 98.9.degree. C.
[0124] The lubricating oils may be derived from synthetic or
natural sources. Mineral oil for use as the base oil in this
invention includes paraffinic, naphthenic and other oils that are
ordinarily used in lubricating oil compositions. Synthetic oils
include hydrocarbon synthetic oils and synthetic esters. Useful
synthetic hydrocarbon oils include liquid polymers of alpha-olefins
having the proper viscosity. Especially useful are the hydrogenated
liquid oligomers of C.sub.6 to C.sub.12 alpha-olefins such as
1-decene trimer. Similarly, alkyl benzenes of proper viscosity,
such as didodecyl benzene, may be used. Useful synthetic esters
include the esters of both mono-carboxylic acids and polycarboxylic
acids as well as mono-hydroxy alkanols and polyols. Typical
examples are didodecyl adipate, pentaerthritol tetracapoate,
di-2-ethylhexyl adipate, di-laurylsebacate and the like. Complex
esters prepared from mixtures of mono- and di-carboxylic acid and
mono- and di-hydroxy alkanols can also be used.
[0125] Blends of hydrocarbon oils and synthetic oils may also be
used. For example, blends of 10 weight percent to 25 weight percent
hydrogenated 1-decene trimer with 75 weight percent to 90 weight
percent 683 centistokes at 37.8.degree. C. mineral oil gives an
excellent oil base. Fischer-Tropsch derived base oils may also be
employed in the lubricating oil composition of the present
invention.
[0126] It is further contemplated that the oil of lubricating
viscosity employed for preparing the lubricating oil composition of
the present invention is a low sulfur base oil. Use of a low sulfur
base oil assists in obtaining a lubricating oil composition which
is ultra low in sulfur content. Sulfur content of base oils is well
known by persons skilled in the art, thus, selection of a low
sulfur base oil may be conveniently made for the purpose of the
present invention.
[0127] Dispersants
[0128] The lubricating oil composition of the present invention
contains dispersants. Typically, the ashless dispersants are
nitrogen-containing dispersants formed by reacting alkenyl succinic
acid anhydride with an amine. Examples of such dispersants are
alkenyl succinimides and succinamides. These dispersants can be
further modified by reaction with, for example, boron or ethylene
carbonate. Ester-based ashless dispersants derived from long chain
hydrocarbon-substituted carboxylic acids and hydroxy compounds may
also be employed. Preferred ashless dispersants are those derived
from polyisobutenyl succinic anhydride. A large number of
dispersants are commercially available.
[0129] Anti-Oxidants
[0130] Anti-oxidants are used in lubricating oils for inhibition of
decomposition processes that occur naturally in lubricating oils as
they age or oxidize in the presence of air. These oxidation
processes may cause formation of gums, lacquers and sludge
resulting in an increase in acidity and viscosity. Examples of
useful anti-oxidants are hindered phenol oxidation inhibitors, such
as 4,4'-methylene-bis(2,6-di-tert-butylphenol),
4,4'-bis(2,6-di-tert-butylphenol),
4,4'-bis(2-methyl-6-tert-butylphenol),
2,2'-methylene-bis(4-methyl-6-tert-butylphenol),
4,4'-butylidene-bis(3-methyl-6-tert-butylphenol),
4,4'-isopropylidene-bis(2,6-di-tert-butylphenol),
2,2'-methylene-bis(4-methyl-6-nonylphenol),
2,2'-isobutylidene-bis(4,6-dimethylphenol),
2,2'-5-methylene-bis(4-methyl-6-cyclohexylphenol),
2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-4-ethylphenol,
2,4-dimethyl-6-tert-butyl-phenol,
2,6-di-tert-I-dimethylamino-p-cresol,
2,6-di-tert-4-(N,N'-di-methylaminomethylphenol),
4,4'-thiobis(2-methyl-6-tert-butylphenol),
2,2'-thiobis(4-methyl-6-tert-butylphenol),
bis(3-methyl-4-hydroxy-5-tert-10-butylbenzyl)-sulfide, and
bis(3,5-di-tert-butyl-4-hydroxybenzyl). Examples of alkylated and
non-alkylated aromatic amines are alkylated diphenylamine,
phenyl-alpha-naphthylamine, and alkylated-alpha-naphthylamine.
Other classes of anti-oxidants are esters of thiodicarboxylic
acids, salts of di-thiophosphoric acids, alkyl or aryl phosphates
and molybdenum compounds, such as amine-molybdenum complex compound
and molybdenum di-thiocarbamates may also be used as anti-oxidants,
provided the molybdenum compounds do not include tri-nuclear
molybdenum. However, their addition of the will contribute to the
phosphorus, sulfur and sulfated ash content of the lubricating
oil.
[0131] Low, Medium and High Overbased Metal Detergents
[0132] Examples of the low and medium overbased metal detergents
employed in the lubricating oil composition of the present
invention are low, medium or high overbased sulfonic acids or
Mannich condensation products of alkylphenols, aldehydes and
amines. It is preferred that the overbased detergents do not
include overbased salicylic acids, carboxylic acids and phenols.
These detergents may be alkali metal detergents or alkaline earth
metal detergents. Preferably they are alkaline earth metal
detergents and more preferably they are calcium detergents. The TBN
of these detergents is greater than 1 and about 500, or more. These
detergents are well known in the art and are commercially
available.
Other Additives
[0133] The lubricating oil composition of the present invention may
also contain, in addition to the additives discussed above, other
additives used to impart desirable properties to the lubricating
oil composition of the present invention. Thus, the lubricating oil
may contain one or more of additives, such as viscosity index
improvers, pour point depressants, demulsifiers, extreme pressure
agents and foam inhibitors. These additional additives are
described in more detail below.
[0134] Viscosity Index Improvers
[0135] Viscosity index improvers are added to lubricating oil to
regulate viscosity changes due to the change in temperature. Some
commercially available examples of viscosity index improvers are
olefin copolymers, such as ethylene-propylene copolymers,
styrene-isoprene copolymers, hydrated styrene-isoprene copolymers,
polybutene, polyisobutylene, polymethacrylates, vinylpyrrolidone
and methacrylate copolymers and dispersant type viscosity index
improvers.
[0136] Extreme Pressure Agents
[0137] Extreme pressure agents that may be used in the lubricating
oil composition of the present invention include alkaline earth
metal borated extreme pressure agents and alkali metal borated
extreme pressure agents. Extreme pressure agents containing
molybdenum may also be employed in the lubricating oil composition
of the present invention, provided the molybdenum compounds do not
include tri-nuclear molybdenum. Sulfurized olefins, zinc
dialky-1-dithiophosphate (primary alkyl, secondary alkyl, and aryl
type), di-phenyl sulfide, methyl tri-chlorostearate, chlorinated
naphthalene, fluoroalkylpolysiloxane, lead naphthenate, neutralized
or partially neutralized phosphates, di-thiophosphates, and
sulfur-free phosphates. The preferred extreme pressure agents are
those that will not contribute to the phosphorus content of the
lubricating oil.
[0138] Pour Point Depressants
[0139] Polymethyl methacrylate is an example of a pour point
depressant useful for addition to the lubricating oil of the
present invention.
[0140] Rust Inhibitors
[0141] Rust inhibitors include nonionic polyoxyethylene surface
active agents, such as polyoxyethylene lauryl ether,
polyoxyethylene higher alcohol ether, polyoxyethylene nonyl phenyl
ether, polyoxyethylene octyl phenyl ether, polyoxyethylene octyl
stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene
sorbitol monostearate, polyoxyethylene sorbitol mono-oleate, and
polyethylene glycol mono-oleate. Other compounds that may also be
employed as rust inhibitors include stearic acid and other fatty
acids, di-carboxylic acids, metal soaps, fatty acid amine salts,
metal salts of heavy sulfonic acid, partial carboxylic acid ester
of polyhydric alcohol, and phosphoric ester. However, preferred
rust inhibitors are those that do not contribute to the phosphorus
or sulfur content of the lubricating oil.
[0142] Corrosion inhibitors
[0143] Corrosion inhibitors are included in lubricating oils to
protect vulnerable metal surfaces. Such corrosion inhibitors are
generally used in very small amounts in the range of from about
0.02 weight percent to about 1.0 weight percent. Examples of
corrosion inhibitors that may be used are sulfurized olefin
corrosion inhibitor and the co-sulfurized alkenyl ester/alpha
olefin corrosion inhibitor. The corrosion inhibitors should not be
a metal di-thiophosphates, especially zinc di-alkyl
di-thiophosphate because addition of this corrosion inhibitor will
contribute to the zinc, phosphorus and sulfur content of the
lubricating oil.
[0144] Friction modifiers
[0145] Friction modifiers that are employable in the lubricating
oil composition of the present invention, include both
ash-containing as well as ashless friction modifiers. Friction
modifiers include, but are not limited to, fatty alcohols, fatty
acids, such as stearic acid, isostearic acid, oleic acid and other
fatty acids or salts and esters thereof, borated esters, amines,
phosphates, and di-, and tri-hydrocarbyl phosphates, hydrocarbyl
phosphites and phosphonates. hydrocarbyl phosphites. Friction
modifiers may also contain molybdenum, provided the molybdenum
compounds do not include tri-nuclear molybdenum. Preferably the
friction modifiers used in the lubricating oil composition of the
present invention are ashless friction modifiers.
[0146] Metal Deactivators
[0147] Metal deactivators that may be employed in the lubricating
oil composition of the present invention include but are not
limited to di-salicylidene propylenediamine, triazole derivatives,
mercaptobenzothiazoles, thiodiazole derivatives, and
mercaptobenzimidazoles.
[0148] Seal Swell Agents
[0149] The lubricating oil composition of the present invention may
employ seal swell agents, including but are not limited to,
di-esters such as di-2-ehtylhexylsebacate, di-octyladipate and
di-2-ethylhexylphthalate, mineral oils with aliphatic alcohols,
such as tri-decyl alcohol and Trisphosphite ester in combination
with a hydrocarbonyl-substituted phenol.
[0150] Demulsifiers
[0151] Addition product of alkylphenol and ethylene oxide,
polyoxyethylene alkyl ether, and polyoxyethylene sorbitan ester may
be employed in the lubricating oil composition of the present
invention.
[0152] Foam Inhibitors
[0153] Useful foam inhibitors for the present invention are alkyl
methacrylate polymers, dimethyl silicone polymers and polysiloxane
type foam inhibitors.
[0154] For best overall results in terms of affording the
properties desired in a conventional lubricating oil composition
for lubricating diesel engines, gasoline engines and natural gas
engines, the lubricating oil may contain a compatible combination
of additives of each of the above classes of additives in effective
amounts.
[0155] The various additive materials or classes of materials
herein described are well known materials and can be readily
purchased commercially or prepared by known procedures or obvious
modification thereof.
[0156] In Table I below are given treatment rates for additives
contemplated for use in the lubricating oil of the present
invention. All component amounts are given as a weight percent of
the active additive. TABLE-US-00001 TABLE I Most Preferred
Preferred Range Range Range Component (wt %) (wt %) (wt %) Borated
and non-borated 0 to 10 2 to 9 2 to 7 Succinimide Dispersant
Anti-oxidants 0 to 3.0 0.2 to 2.0 0.2 to 1.5 Neutral or Metal 0 to
10 1 to 8 1 to 5 Overbased Detergent Viscosity Index Improvers 0 to
10 2 to 9 3 to 8 Extreme Pressure Agents 0 to 2.0 0 to 1.0 0.1 to
0.5 Pour Point Depressants 0 to 1.0 0.05 to 0.5 0.05 to 0.3 Rust
Inhibitors 0 to 1.0 0 to 0.75 0.05 to 0.5 Corrosion Inhibitors 0 to
3.0 0.2 to 2.0 0.2 to 1.5 Friction Modifiers 0 to 1.0 0.05 to 0.75
0.1 to 0.5 Foam Inhibitors 0 to 3.0 0.2 to 2.0 0.2 to 1.5
EXAMPLES
[0157] The low sulfur and low phosphorus lubricating oil
composition of the present invention was evaluated for its
anti-wear performance in formulations prepared as described in
Example 1 and Table I below.
Example 1
[0158] Comparative Formulation A and Test Formulation B contained
two dispersants, two anti-oxidants, a low overbased and a high
overbased sulfonate, a corrosion inhibitor and an anti-foaming
agent. Base oil was used to make-up a 100 percent of each of
Comparative Formulation A and Test Formulation B.
[0159] The anti-wear performance of Test Formulation B was compared
with Comparative Formulation A which contained zinc di-alkyl
di-thiophosphate in addition to the other components given above.
The degree of wear control with Test Formulation B was determined
as a reduction in cylinder liner wear compared with Comparative
Formulation A.
[0160] Comparative Formulation A and Test Formulation B are
described in more detail in Table II below. The amounts of the
components in the lubricating oil formulations are given in Table
II in weight percent active additive. TABLE-US-00002 TABLE II
Formulation (weight %) Component Comparative Formulation A Test
formulation B Base Oil Borated Dispersant 1.0 1.0 Non-borated 5.7
5.7 Dispersant Low Overbased 0.4 0.4 Calcium Sulfonate High
Overbased 0.8 0.8 Calcium Sulfonate Molybdenum Anti- 0.12 0.12
oxidant Phenolic Anti- 0.11 0.11 oxidant Corrosion Inhibitor 0.8
0.8 Foam Inhibitor 0.02 0.02 Zinc Di-alkyl Di- 1.4 0.0
thiophosphate
[0161] Table III below shows the amount of the sulfur and
phosphorus in Comparative Formulation A and Test Formulation B.
TABLE-US-00003 TABLE III (weight %) Component Comparative
Formulation A Test Formulation C Sulfur 0.35 0.04 Phosphorus 0.16
0.00
Example 2
Cylinder Liner Wear Test
[0162] The anti-wear control of Test Formulation B was compared to
Comparative Formulation A was evaluated as described below.
[0163] Wear measurements were performed in a Mack Diesel Engine,
installed in an engine test laboratory. The engine stand
configuration was in conformance to the Mack T-10 engine test
procedure known as ASTM Test Method D-6987. In addition, the engine
was equipped with radiated cylinder liners and a system to
circulate the engine lubricant through an external reservoir. A
detector was placed in the reservoir to count the gamma-rays from
the oil being circulated past the detector. The increase in the
gamma-ray count over a fixed period of time is a measure of the
amount of metal weight loss from the radiated area, in this case
the cylinder liner area around the top ring reversal point.
[0164] The data reported were measured wear at the end of the test.
The results of the Cylinder Liner Wear Test are summarized in Table
IV below. TABLE-US-00004 TABLE IV Cylinder Liner Wear Test
Comparative Formulation A Test Formulation B Measured Wear 38.4
10.4 (nanometers/hour)
[0165] The results obtained in the Cylinder Liner Wear Test
summarized above in Table IV show that the cylinder liner wear
measured for Comparative Formulation A containing a zinc di-alkyl
di-thiophosphate was 38.4 nanometers per hour, while the cylinder
liner wear measured for Test Formulation B containing no zinc
di-alkyl di-thiophosphate was 10.4 nanometers per hour. The data
show that leaving out the zinc di-alkyl di-thiophosphate from Test
Formulation B gave a 73 percent reduction in cylinder liner wear
compared to the cylinder liner wear observed with Comparative
Formulation A containing a zinc di-alkyl di-thiophosphate.
[0166] The results of the cylinder liner wear test summarized in
Table IV above show that Test Formulation B without zinc di-alkyl
di-thiophosphate performed significantly better than Comparative
Formulation A which contained zinc di-alkyl di-thiophosphate. This
result was unexpected since zinc di-alkyl di-thiophosphate is a
conventionally used anti-wear additive in lubricating oil. Based on
conventional wisdom, this was a surprising result.
* * * * *