U.S. patent application number 14/772082 was filed with the patent office on 2016-01-28 for lubricating composition.
The applicant listed for this patent is SHELL OIL COMPANY. Invention is credited to Richard Thomas DIXON, Gillian Elizabeth HUNT.
Application Number | 20160024418 14/772082 |
Document ID | / |
Family ID | 47790076 |
Filed Date | 2016-01-28 |
United States Patent
Application |
20160024418 |
Kind Code |
A1 |
DIXON; Richard Thomas ; et
al. |
January 28, 2016 |
LUBRICATING COMPOSITION
Abstract
The present invention provides a lubricating composition
comprising: (i) a base oil; (ii) a non-silicone anti-foam agent;
and (iii) one or more performance additives; wherein the
composition has a kinematic viscosity at 100.degree. C. (according
to ASTM D445) of 16.3 mm.sup.2/s or less, a low temperature
cranking viscosity of at most 6600 cP at -30.degree. C. (ASTM
D5293) and a NOACK volatility of at most 11% according to
CEC-L-40-93.
Inventors: |
DIXON; Richard Thomas;
(Chester, Cheshire, GB) ; HUNT; Gillian Elizabeth;
(Ince, Cheshire, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL OIL COMPANY |
Houston |
TX |
US |
|
|
Family ID: |
47790076 |
Appl. No.: |
14/772082 |
Filed: |
March 4, 2014 |
PCT Filed: |
March 4, 2014 |
PCT NO: |
PCT/EP2014/054189 |
371 Date: |
September 2, 2015 |
Current U.S.
Class: |
508/463 |
Current CPC
Class: |
C10N 2010/04 20130101;
C10N 2040/25 20130101; C10M 169/04 20130101; C10N 2030/18 20130101;
C10N 2020/02 20130101; C10M 2209/084 20130101; C10M 2205/173
20130101; C10M 171/004 20130101; C10N 2030/02 20130101; C10M
2229/02 20130101; C10N 2030/74 20200501; C10M 145/14 20130101 |
International
Class: |
C10M 145/14 20060101
C10M145/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 4, 2013 |
EP |
13157585.4 |
Claims
1. A lubricating composition comprising: (i) a base oil; (ii) a
non-silicone anti-foam agent; and (iii) one or more performance
additives; wherein the composition has a kinematic viscosity at
100.degree. C. (according to ASTM D445) of 16.3 mm.sup.2/s or less,
a low temperature cranking viscosity of at most 6600 cP at
-30.degree. C. (ASTM D5293) and a NOACK volatility of at most 11%
according to CEC-L-40-93.
2. Lubricating composition according to claim 1, wherein the
composition has a NOACK volatility of at most 10.5% according to
CEC-L-40-93.
3. Lubricating composition according to claim 1, wherein the
non-silicone anti-foam agent is selected from acrylate,
polyacrylate, and polymethacrylate (PMA) polymers.
4. Lubricating composition according to claim 1, wherein the
non-silicone anti-foam agent is present at a level of from 10 ppm
to 500 pm, by weight of the composition.
5. Lubricating composition according to claim 1, wherein the base
oil comprises one or more Fischer-Tropsch derived base oils.
6. Lubricating composition according to claim 5, wherein the base
oil comprises 80% or greater of one or more Fischer-Tropsch derived
base oils, by weight of the base oil.
7. Lubricating composition according to claim 1, wherein the
composition is essentially free of polyalphaolefin base oil.
8. Lubricating composition according to claim 1, wherein the one or
more performance additives comprises a silicone-based anti-foam
agent.
9. (canceled)
10. (canceled)
11. A method of lubrication comprising applying a lubricating
composition to a crankcase of an engine, wherein the lubricating
composition comprises: (i) a base oil; (ii) a non-silicone
anti-foam agent; and (iii) one or more performance additives;
wherein the composition has a kinematic viscosity at 100.degree. C.
(according to ASTM D445) of 16.3 mm.sup.2/s or less, a low
temperature cranking viscosity of at most 6600 cP at -30.degree. C.
(ASTM D5293) and a NOACK volatility of at most 11% according to
CEC-L-40-93.
12. The method according to claim 11, wherein the non-silicone
anti-foam agent is an alkyl polyacrylate anti-foam agent.
13. The method according to claim 11, wherein the composition has a
NOACK volatility of at most 10.5% according to CEC-L-40-93.
14. The method according to claim 11, wherein the non-silicone
anti-foam agent is selected from acrylate, polyacrylate, and
polymethacrylate (PMA) polymers.
15. The method according to claim 11, wherein the non-silicone
anti-foam agent is present at a level of from 10 ppm to 500 pm, by
weight of the composition.
16. The method according to claim 11, wherein the base oil
comprises one or more Fischer-Tropsch derived base oils.
17. The method according to claim 11, wherein the base oil
comprises 80% or greater of one or more Fischer-Tropsch derived
base oils, by weight of the base oil.
18. The method according to claim 11, wherein the composition is
essentially free of polyalphaolefin base oil.
19. The method according to claim 11, wherein the one or more
performance additives comprises a silicone-based anti-foam agent.
Description
[0001] The present invention relates to a lubricating composition
comprising a base oil and one or more performance additives for
particular use in the crankcase of an internal combustion engine,
in particular an internal combustion engine used in a passenger
vehicle or light duty van.
[0002] In practice various lubricating compositions for crankcase
engines are known. A disadvantage of known crankcase engine oils is
that, especially when they are based on conventional mineral Group
III base oils, they may have undesirable fuel economy oil
performance values, it being problematic to blend to lower SAE J300
viscosity grades. A further problem of known crankcase engine oils
is that they may have undesirable properties for one or more of
wear performance and NOACK volatility, particularly when blending
to lower SAE J300 viscosity grades.
[0003] Attempts have been made to overcome the above problems by
formulating with non-mineral oil Group III base oils, such as
Fischer-Tropsch derived base oils. WO2010020653 discloses the use
of Fischer-Tropsch base oils in lubricating compositions. The
composition of Example 1 of WO2010020653 shows a surprisingly low
NOACK volatility when compared to the composition of Comparative
Example 1 (using a Group III mineral base oil).
[0004] However, it has been found that in low viscosity
formulations such as 0W-30 and 0W-40 engine oils, the use of
Fischer-Tropsch base oils may not be enough on their own to provide
the low NOACK volatility values desired for such formulations.
[0005] One way to further lower the NOACK volatility is to use a
combination of polyalphaolefin base oils in addition to a
Fischer-Tropsch derived base oil. However, polyalphaolefin base
oils are relatively expensive and therefore it would be desirable
to find an alternative way of lowering the NOACK volatility of
0W-30 and 0W-40 formulations, particularly those formulations
comprising Fischer-Tropsch derived base oils.
[0006] It has surprisingly been found that by including a
non-silicone anti-foam agent in the lubricating formulation the
NOACK volatility can be lowered to desirable levels.
[0007] Hence according to the present invention there is provided a
lubricating composition comprising:
(i) a base oil; (ii) a non-silicone anti-foam agent; and (iii) one
or more performance additives; wherein the lubricating composition
has a kinematic viscosity at 100.degree. C. (according to ASTM
D445) of 16.3 mm.sup.2/s or less, a low temperature cranking
viscosity of at most 6600 cP at -30.degree. C. (ASTM D5293) and a
NOACK volatility of at most 11% according to CEC-L-40-93.
[0008] According to another aspect of the present invention there
is provided the use of a non-silicone anti-foam agent for reducing
the NOACK volatility of a lubricating composition, in particular
wherein the lubricating composition comprises a Fischer-Tropsch
base oil.
[0009] Another important advantage of the present invention is that
the lubricating composition has a desirably low cold-crank
viscosity (i.e. dynamic viscosity according to ASTM D 5293), i.e. a
cranking viscosity of at most 6600 cP at -30.degree. C. (ASTM
D5293).
[0010] It is an advantage of the present invention that it allows
the formulation of alternative SAE J300 0W-30 and 0W-40 crankcase
engine oils.
[0011] There are no particular limitations regarding the base oil
used in the lubricating composition according to the present
invention, and various conventional mineral oils, synthetic oils as
well as naturally derived esters such as vegetable oils may be
conveniently used, provided that the requirements in respect of the
lubricant composition according to the present invention are
met.
[0012] The base oil used in the present invention may conveniently
comprise mixtures of one or more mineral oils and/or one or more
synthetic oils; thus, according to the present invention, the term
"base oil" may refer to a mixture containing more than one base
oil. Mineral oils include liquid petroleum oils and solvent-treated
or acid-treated mineral lubricating oil of the paraffinic,
naphthenic, or mixed paraffinic/naphthenic type which may be
further refined by hydrofinishing processes and/or dewaxing.
[0013] Suitable base oils for use in the lubricating oil
composition of the present invention are Group III mineral base
oils, Group IV poly-alpha olefins (PAOs), Group III Fischer-Tropsch
derived base oils and mixtures thereof.
[0014] By "Group III" and "Group IV" base oils in the present
invention are meant lubricating oil base oils according to the
definitions of American Petroleum Institute (API) for category III
and IV. These API categories are defined in API Publication 1509,
15th Edition, Appendix E, April 2002.
[0015] Fischer-Tropsch derived base oils are known in the art. By
the term "Fischer-Tropsch derived" is meant that a base oil is, or
is derived from, a synthesis product of a Fischer-Tropsch process.
A Fischer-Tropsch derived base oil may also be referred to as a GTL
(Gas-To-Liquids) base oil. Suitable Fischer-Tropsch derived base
oils that may be conveniently used as the base oil in the
lubricating composition of the present invention are those as for
example disclosed in EP 0 776 959, EP 0 668 342, WO 97/21788, WO
00/15736, WO 00/14188, WO 00/14187, WO 00/14183, WO 00/14179, WO
00/08115, WO 99/41332, EP 1 029 029, WO 01/18156 and WO
01/57166.
[0016] Synthetic oils include hydrocarbon oils such as olefin
oligomers (including polyalphaolefin base oils; PAOs), dibasic acid
esters, polyol esters, polyalkylene glycols (PAGs), alkyl
naphthalenes and dewaxed waxy isomerates. Synthetic hydrocarbon
base oils sold by the Shell Group under the designation "Shell
XHVI" (trade mark) may be conveniently used.
[0017] Poly-alpha olefin base oils (PAOs) and their manufacture are
well known in the art. Suitable poly-alpha olefin base oils that
may be used in the lubricating compositions of the present
invention may be derived from linear C.sub.2 to C.sub.32,
preferably C.sub.6 to C.sub.16, alpha olefins. Particularly
preferred feedstocks for said poly-alpha olefins are 1-octene,
1-decene, 1-dodecene and 1-tetradecene.
[0018] Preferably, the base oil as used in the lubricating
composition according to the present invention comprises a
Fischer-Tropsch derived base oil.
[0019] There is a strong preference for using a Fischer-Tropsch
derived base oil over a PAO base oil, in view of the high cost of
manufacture of the PAOs. Thus, preferably, the base oil contains
more than 50 wt. %, preferably more than 60 wt. %, more preferably
more than 70 wt. %, even more preferably more than 80 wt. %. most
preferably more than 90 wt. % Fischer-Tropsch derived base oil. In
an especially preferred embodiment not more than 5 wt. %,
preferably not more than 2 wt. %, of the base oil is not a
Fischer-Tropsch derived base oil. In a preferred embodiment herein,
the lubricating composition is essentially free of polyalphaolefin
base oil, i.e. no more than 2 wt. % of the base oil is a
polyalphaolefin base oil. In a particularly preferred embodiment
herein, the lubricating composition is free of polyalphaolefin base
oil. In another preferred embodiment herein 100 wt % of the base
oil is based on one or more Fischer-Tropsch derived base oils.
[0020] The total amount of base oil incorporated in the lubricating
composition of the present invention is preferably present in an
amount in the range of from 60 to 99 wt. %, more preferably in an
amount in the range of from 65 to 90 wt. % and most preferably in
an amount in the range of from 70 to 85 wt. %, with respect to the
total weight of the lubricating composition.
[0021] According to the present invention the base oil (or base oil
blend) preferably has a kinematic viscosity at 100.degree. C. of at
least 3.5 cSt (according to ASTM D445), preferably at least 3.8 cSt
and most preferably at least 4.1 cSt.
[0022] The lubricating composition of the present invention further
comprises a non-silicone anti-foam agent. As used herein the term
"anti-foam agent" is a compound which is added into a lubricating
composition at low levels (typically at a level of about 10 ppm to
about 500 ppm) to help dissipate surface air bubbles.
[0023] Preferably, the non-silicone anti-foam agent is selected
from acrylate, polyacrylate, and polymethacrylate (PMA) polymers. A
preferred non-silicone anti-foam agent for use herein is a
polyacrylate anti-foam agent. As used herein the term polyacrylate
anti-foam agent includes alkyl polyacrylate anti-foam agents and
acrylic copolymers.
[0024] The non-silicone anti-foam agent is preferably present at a
level of from 10 ppm to 500 ppm, preferably from 30 ppm to 200 ppm,
more preferably from 100 ppm to 200 ppm, by weight of the
lubricating composition.
[0025] An example of a suitable alkyl polyacrylate anti-foam agents
is PC1644 commercially available from Cytec. PC1644 is an acrylic
copolymer comprising ethylacrylate and 2-ethylhexylacrylate
copolymer. Another commercially available alkyl polyacrylate
anti-foam agent for use herein is PC2544 commercially available
from Cytec. PC2544 is a modified acrylic copolymer.
[0026] As mentioned above, the lubricating composition according to
the present invention meets certain specific requirements for the
dynamic viscosity at -30.degree. C., the kinematic viscosity at
100.degree. C. and the NOACK volatility.
[0027] Typically, the dynamic viscosity at -30.degree. C.
(according to ASTM D 5293) of the composition is at most 6600
cP.
[0028] Typically, the dynamic viscosity at -35.degree. C.
(according to ASTM D 5293) of the composition is at most 6200
cP.
[0029] Typically, the kinematic viscosity at 100.degree. C.
(according to ASTM D 445) of the composition is at most 16.3 cSt,
preferably from 9.3 to 16.3 cSt, more preferably from 9.3 and 12.5
cSt.
[0030] Typically, the high temperature, high shear viscosity
("HTHS"; according to ASTM D 4683) of the lubricating composition
is in the range of from 2.9 to 3.7 mPas, preferably in the range of
from 2.9 to 3.5 mPas.
[0031] Typically, the NOACK volatility (according to CEC-L-40-93)
of the composition is 11 wt % or below, preferably 10.5 wt % or
below, even more preferably 10.0 wt. % or below. Typically the
NOACK volatility (according to CEC-L-40-93) is at least 8 wt.
%.
[0032] The lubricating composition according to the present
invention further comprises one or more additives such as
anti-oxidants, anti-wear additives, dispersants, detergents,
overbased detergents, extreme pressure additives, friction
modifiers, viscosity index improvers, pour point depressants, metal
passivators, corrosion inhibitors, demulsifiers, anti-foam agents,
seal compatibility agents and additive diluent base oils, etc.
[0033] As the person skilled in the art is familiar with the above
and other additives, these are not further discussed here in
detail. Specific examples of such additives are described in for
example Kirk-Othmer Encyclopedia of Chemical Technology, third
edition, volume 14, pages 477-526.
[0034] A preferred additive is a silicone-based anti-foam agent
which can be present on its own or as part of a performance
additive package. The silicone-based anti-foam agent is preferably
present at a level of from 20 to 200 ppm, by weight of the
lubricating composition.
[0035] A preferred silicone-based anti-foam agent is a
polysiloxane. A silicone-based anti-foam agent is particularly
useful herein in combination with a non-silicone anti-foam agent
for providing a lubricating composition having reduced NOACK
volatility.
[0036] Anti-oxidants that may be conveniently used include
phenyl-naphthylamines (such as "IRGANOX L-06" available from Ciba
Specialty Chemicals) and diphenylamines (such as "IRGANOX L-57"
available from Ciba Specialty Chemicals) as e.g. disclosed in WO
2007/045629 and EP 1 058 720 B1, phenolic anti-oxidants, etc. The
teaching of WO 2007/045629 and EP 1 058 720 B1 is hereby
incorporated by reference.
[0037] Anti-wear additives that may be conveniently used include
zinc-containing compounds such as zinc dithiophosphate compounds
selected from zinc dialkyl-, diaryl- and/or
alkylaryl-dithiophosphates, molybdenum-containing compounds,
boron-containing compounds and ashless anti-wear additives such as
substituted or unsubstituted thiophosphoric acids, and salts
thereof.
[0038] Examples of such molybdenum-containing compounds may
conveniently include molybdenum dithiocarbamates, trinuclear
molybdenum compounds, for example as described in WO 98/26030,
sulphides of molybdenum and molybdenum dithiophosphate.
[0039] Boron-containing compounds that may be conveniently used
include borate esters, borated fatty amines, borated epoxides,
alkali metal (or mixed alkali metal or alkaline earth metal)
borates and borated overbased metal salts.
[0040] The dispersant used is preferably an ashless dispersant.
Suitable examples of ashless dispersants are polybutylene
succinimide polyamines and Mannich base type dispersants.
[0041] The detergent used is preferably an overbased detergent or
detergent mixture containing e.g. salicylate, sulphonate and/or
phenate-type detergents.
[0042] Examples of viscosity index improvers which may conveniently
be used in the lubricating composition of the present invention
include the styrene-butadiene stellate copolymers, styrene-isoprene
stellate copolymers and the polymethacrylate copolymer and
ethylene-propylene copolymers. Dispersant-viscosity index improvers
may be used in the lubricating composition of the present
invention.
[0043] Preferably, the composition contains at least 0.1 wt. % of a
pour point depressant. As an example, alkylated naphthalene and
phenolic polymers, polymethacrylates, maleate/fumarate copolymer
esters may be conveniently used as effective pour point
depressants. Preferably not more than 0.3 wt. % of the pour point
depressant is used.
[0044] Furthermore, compounds such as alkenyl succinic acid or
ester moieties thereof, benzotriazole-based compounds and
thiodiazole-based compounds may be conveniently used in the
lubricating composition of the present invention as corrosion
inhibitors.
[0045] Compounds which may be conveniently used in the lubricating
composition of the present invention as seal fix or seal
compatibility agents include, for example, commercially available
aromatic esters.
[0046] The lubricating compositions of the present invention may be
conveniently prepared by admixing the one or more additives,
including the non-silicone anti-foam agent, with the base
oil(s).
[0047] The above-mentioned additives are typically present in an
amount in the range of from 0.01 to 35.0 wt. %, based on the total
weight of the lubricating composition, preferably in an amount in
the range of from 0.05 to 25.0 wt. %, more preferably from 1.0 to
20.0 wt. %, based on the total weight of the lubricating
composition.
[0048] Preferably, the composition contains from 10 wt. % to 15 wt.
% of an additive package comprising a combination of additives
including anti-oxidants, a zinc-based anti-wear additive, an
ashless dispersant, an overbased detergent mixture, and a
silicone-based anti-foaming agent.
[0049] According to an especially preferred embodiment of the
present invention, the composition meets the requirements of an SAE
J300 0W-30 or 0W-40 formulation, preferably those of a 0W-30
formulation.
[0050] In another aspect, the present invention provides the use of
a non-silicone anti-foam agent for reducing the NOACK volatility of
lubricating composition, in particular wherein the lubricating
composition comprises a Fischer-Tropsch derived base oil.
[0051] Also the present invention provides a method of improving
NOACK volatility properties, which method comprises lubricating the
crankcase of an engine, in particular a passenger car motor engine,
with a lubricating composition according to the present
invention.
[0052] The present invention is described below with reference to
the following Examples, which are not intended to limit the scope
of the present invention in any way.
EXAMPLES
Lubricating Oil Compositions
[0053] Various engine oils for use in a crankcase engine were
formulated.
[0054] Table 1 indicates the properties for the base oils used.
TABLE-US-00001 TABLE 1 Base oil 1 Base oil 2 (GTL4) (GTL8)
Kinematic viscosity at 4.2 8.5 100.degree. C..sup.1 [cSt] VI
Index.sup.2 120 120 NOACK volatility.sup.3 14 5 [wt. %]
.sup.1According to ASTM D 445 .sup.2According to ASTM D 2270
.sup.3According to CEC L-40-A-93/ASTM D 5800
[0055] Table 2 indicates the composition and properties of the
fully formulated engine oil formulations that were tested; the
amounts of the components are given in wt. %, based on the total
weight of the fully formulated formulations.
[0056] All tested engine oil formulations contained a combination
of a base oil, an additive package (Additive Package 1), and a
supplementary additive package (Additive Package 2), which additive
packages were the same in all tested compositions.
[0057] Additive package 1 was Infineum P6660 commercially available
from Infineum which contained a combination of additives including
anti-oxidants, a zinc-based anti-wear additive, an ashless
dispersant, an overbased detergent mixture, and a silicone-based
anti-foaming agent.
[0058] Additive package 2 contained a combination of a dispersant,
anti-oxidant and a friction modifier.
[0059] Examples 1 to 6 contained a non-silicone anti-foam agent.
The non-silicone anti-foam agents were alkyl polyacrylate anti-foam
agents with the tradenames PC1644 and PC2544 commercially available
from Cytec.
[0060] Comparative Examples 2 to 4 contained a silicone-containing
anti-foam agent (Synative AC AMH-2 commercially available from
Cognis).
[0061] In all formulations, a conventional viscosity modifier
concentrate was used to adjust the viscosity and a conventional
pour point depressant was used to adjust the pour point.
[0062] "Base oil 1" was a Fischer-Tropsch derived base oil ("GTL
4") having a kinematic viscosity at 100.degree. C. (ASTM D445) of
approx. 4 cSt (mm.sup.2s.sup.-1).
[0063] "Base oil 2" was a Fischer-Tropsch derived base oil ("GTL
8") having a kinematic viscosity at 100.degree. C. (ASTM D445) of
approx. 8 cSt (mm.sup.2s.sup.-1).
[0064] These GTL 4 and GTL 8 base oils may be conveniently
manufactured by the process described in e.g. WO-A-02/070631, the
teaching of which is hereby incorporated by reference.
[0065] The compositions of Examples 1 to 6 and Comparative Example
1 to 4 were obtained by mixing the base oils with the additive
package and the anti-foam agent, where present, using conventional
lubricant blending procedures.
[0066] The composition of Comparative Examples 1-4 and Examples 1-6
met the requirements of a 0W-30 formulation, according to SAE
J300.
[0067] The lubricating compositions of the Examples and Comparative
Examples were subjected to various test methods as indicated in
Table 2 in order to determine their NOACK volatility, their dynamic
viscosity at -35.degree. C. and their kinematic viscosity at
100.degree. C. The results are shown in Table 2.
TABLE-US-00002 TABLE 2 Comp. Comp. Comp. Comp. Component [wt. %]
Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6
Additive Package 1 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3
13.3 Additive Package 2 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6 1.6
Pour Point Depressant 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3
Viscosity Modifier 7.8 7.8 7.8 7.8 7.8 7.8 7.8 7.8 7.8 7.8 Synative
AC AMH-2 -- 0.003 0.01 0.02 -- -- -- -- -- PC1644 -- -- -- -- 0.003
0.01 0.02 -- -- -- PC2544 -- -- -- -- -- -- -- 0.003 0.01 0.02 GTL
4 71 71 71 71 71 71 71 71 71 71 GTL 8 6 5.997 5.99 5.98 5.997 5.99
5.98 5.997 5.99 5.98 Total 100 100 100 100 100 100 100 100 100 100
Vk100.sup.1 12.06 12.06 12.06 12.06 12.06 12.06 12.06 12.06 12.06
12.06 Vd-35.sup.2 6041 6041 6041 6041 6041 6041 6041 6041 6041 6041
NOACK.sup.3, %/m 11.5 11.4 11.2 11.1 10.1 10.3 9.9 10.7 10.2 10.1
.sup.1According to ASTM D445 .sup.2According to ASTM D5293
.sup.3According to CEC-L-40-93
DISCUSSION
[0068] As can be learned from Table 2, Examples 1-6 containing a
non-silicone anti-foam agent at 30 ppm, 100 ppm and 200 ppm, have
significantly lower NOACK volatility values than Comparative
Examples 1-4 (not containing any non-silicone anti-foam agent).
[0069] An important advantage of the present invention is that
0W-30 formulations meeting stringent NOACK volatility requirements
(e.g. less than or equal to 10 wt. %) can be obtained without the
need to use (relatively expensive) poly-alpha olefin (PAO) base
oils.
* * * * *