Lubricant composition containing thiadiazoles and napthylamines as antioxidants and method of lubrication using said composition

Abstract

Lubricating compositions comprising oil of lubricating viscosity, certain sulfur-containing compounds and naphthyl amines having outstanding resistance to deterioration by oxidation. Improved methods of lubricating engines are also disclosed.

Parent Case Text

This application is a continuation-in-part of application Ser. No. 161,947, filed July 9, 1971 and now U.S. Pat. No. 3,775,321.

Description

This invention relates to new and improved lubricating oil compositions. More particularly, it relates to lubricating compositions having improved resistance to deterioration by oxidation.

One problem involved in producing a lubricating oil composition is the necessity of protecting the composition from deterioration by oxidation. Conventional additives are known to give a degree of protection against oxidation. However, as the lubricating oil technology develops, oils having the ability for longer service, for example in engines such as diesel engines and gas turbines, at severe conditions, e.g., high temperatures, are required. Therefore, the need for improved oxidation resistance in lubricating oil compositions manifests itself.

Therefore, one object of the present invention is to provide a lubricating oil composition having improved resistance toward deterioration by oxidation. Other objects and advantages of the present invention will become apparent hereinafter.

It has now been discovered that the above-noted objects are accomplished by the compositions of the present invention. In one aspect, the present invention is a lubricating oil composition which comprises a major proportion of oil of lubricating viscosity; at least one sulfur-containing compound having the following structure ##EQU1## wherein each R.sup.1 is a monovalent essentially hydrocarbon radical containing from 1 to about 30 carbon atoms, x and y each are integers from 1 to about 9, the sum of x and y being at least 2, and at least one naphthyl amine having the following structure ##SPC1##

Wherein R.sup.2 is selected from the group consisting of hydrogen and monovalent essentially hydrocarbon radicals containing from 1 to about 30, preferably from about 6 to about 18 carbon atoms, a is an integer from zero to 7, preferably zero to 1 inclusive and D is a monovalent essentially hydrocarbon radical containing from 1 to about 30, preferably from about 1 to about 18 carbon atoms, the sulfur-containing component and the naphthyl amine each being present in an amount sufficient to improve the resistance to oxidation of the lubricating oil composition.

It has been found that the combination of the sulfur-containing compound and naphthyl amine imparts significantly superior oxidation resistance to the lubricating oil composition than would be expected based upon the oxidation inhibition achieved using only one of these materials. It is preferred that the sulfur-containing compound be present in an amount from about 0.005% to about 10%, more preferably from about 0.005% to about 2.0%, by weight of the total composition. In certain instances, e.g. when the present compositions are used to lubricate internal combustion engines comprising silver components requiring lubrication, it is particularly useful to use the sulfur-containing compound in an amount from about 0.02% to about 10%, more preferably from about 0.05% to about 2%, by weight of the composition. It is preferred that the naphthyl amine be present in a concentration of at least about 0.05%, more preferably at least about 0.10%, by weight of the total composition. For economic reasons, it is preferred that the naphthyl amine be present in a concentration from about 0.05% to about 2.0%, more preferably from about 0.1% to about 1.0%, of the total composition.

The base oils used in the compositions of the present invention are those conventionally used in lubricant manufacture. Typical examples of the suitable lubricating oils include those having a viscosity within the range of about 50 SUS to about 2000 SUS, preferably from about 500 SUS to about 1200 SUS, at 100.degree.F. These oils may be refined or otherwise processed to produce the desired quality. Although mineral oils are preferred, the base oil may be synthetic in nature. A specific example of the oils used in the present invention is a mineral oil mixture having a viscosity of about 900 SUS at 100.degree.F. Combinations or mixtures of two or more different base oils in a single lubricating composition are often used to provide the desired physical properties and these mixtures are, therefore, within the scope of the present invention. The base oil comprises a major portion, preferably at least about 70%, still more preferably at least about 85%, by weight of the total composition.

The general formula for the suitable sulfur-containing compounds is ##EQU2## wherein each R.sup.1 is the same or different monovalent essentially hydrocarbon radicals, x and y each are integers from 1 to about 9, preferably from 1 to 3, and the sum of x and y is at least 2, and preferably 4 to about 16. The radicals R.sup.1 can be aliphatic or aromatic including acyclic, alicyclic, aralkyl, aryl and alkaryl radicals and mixtures of such radicals. The essentially hydrocarbon radicals can contain from 1 to about 30 carbon atoms, and preferably from about 1 to about 18 carbon atoms. More preferably, each essentially hydrocarbon R.sup.1 is independently selected from the group consisting of alkyl, aralkyl and alkaryl containing up to about 18 carbon atoms. The most preferred sulfur-containing compounds are those in which each essentially hydrocarbon R.sup.1 is alkyl having from 1 to about 18 carbon atoms and x and y each are integers from 1 to 3. Examples of suitable monovalent hydrocarbon radicals are ethyl, propyl, butyl, hexyl, octyl, nonyl, decyl, dodecyl, tridecyl, hexadecyl, octadecyl, cyclo-hexyl, phenyl, tolyl, benzyl, naphthyl, styryl and the like. These sulfur-containing compounds and methods for their preparation are described in U.S. Pat. No. 2,719,126.

The naphthyl amines suitable for use in the present invention comprise a broad class of compounds. The general structural formula for these compounds is as follows: ##SPC2##

wherein R.sup.2 is selected from the group consisting of hydrogen and monovalent essentially hydrocarbon radicals containing from 1 to about 30, preferably from about 6 to about 18 carbon atoms, a is an integer from zero to 7, preferably zero to 1 inclusive, D is an monovalent essentially hydrocarbon radical containing from 1 to about 30, preferably from about 1 to about 18 carbon atoms. Included among the monovalent hydrocarbon radicals contemplated by the present invention are, for example, alkyl, aryl, aralkyl, alkaryl and substituted counterparts of these radicals. Included among the suitable amines are phenyl alpha- or beta-naphthylamine, octylphenyl alpha- or beta- naphthylamine, alpha-alpha, alpha-beta or beta-beta dinaphthylamines, various phenanthryl-anthyrl-naphthylamines, xylyl naphthylamines, dodecyl phenyl naphthylamines, biphenyl naphthylamines and phenyl naphthylamines alkylated with olefins containing from about 8 to about 24 carbon atoms per molecule. Specific examples of these olefins include pinene, .alpha.-methylstyrene, and the like. The naphthylamines in which the essentially hydrocarbon R.sup.2 is a radical selected from the group consisting of aryl and alkaryl containing from 6 to about 18 carbon atoms are of particular usefulness in the present invention and are, therefore, the more preferred class of compounds for use in the present invention. A particularly preferred naphthyl amine is phenyl alpha naphthylamine.

By "essentially hydrocarbon" (i.e., hydrocarbonaceous) radical is meant those radicals which are composed mainly of hydrogen and carbon, and include such radicals which contain, in addition, minor amounts of substituents, such as chlorine, bromine, oxygen, sulfur, nitrogen and the like, which do not substantially affect their hydrocarbon nature and do not substantially adversely affect the functionality of the material, e.g., sulfur-containing compound, naphthyl amine, etc., which contains such radical.

In order to improve the detergent qualities of the compositions of the present invention, it is preferred to include from about 0.1% to about 10%, more preferably from about 0.1% to about 5%, by weight of at least one sulfonate selected from the group consisting of alkali metal sulfonate, alkaline earth metal sulfonate and mixtures thereof. The preferred sulfonates for use in the compositions of the present invention are the alkaline earth metal sulfonates, more preferably the calcium sulfonates.

Sulfonates derived from sulfonic acids having about 12 to about 200 carbon atoms per molecule are of particular usefulness in the present invention. Among these sulfonic acids are mono- and polyalkyl substituted naphthalene sulfonic acids, phenol sulfonic acids, diphenyl ether sulfonic acids, diphenyl ether disulfonic acids, diphenyl sulfide-sulfonic acids, di-naphthylsulfide-sulfonic acids, diphenyl amine-sulfonic acids, phenylnaphthylsulfide sulfonic acids, cycloaliphatic sulfonic acids, such as petroleum naphthene sulfonic acids, cetylcyclopentyl sulfonic acids, lauryl-cyclohexyl sulfonic acids, bis-(diisobutyl)- cyclohexyl sulfonic acids, mono- and poly-wax substituted cyclohexyl sulfonic acids, etc.

With respect to the sulfonic acids, it is intended herein to employ the term "petroleum sulfonic acids" to cover all sulfonic acids which are derived at least in part from petroleum sources. Additional examples of sulfonic acids and/or the alkali and alkaline earth metal salts thereof which can be employed as starting materials are disclosed in the following U.S. Pat. Nos.: 2,174,110; 2,174,560; 2,174,508; 2,193,824; 2,197,800; 2,020,791; 2,212,786; 2,213,360; 2,228,598; 2,233,676; 2,239,974; 2,263,312; 2,276,090; 2,276,097; 2,315,514; 2,319,121; 2,321,022; 2,333,568; 2,333,788; 2,335,259; 2,337,552; 2,346,568; 2,366,027; 2,374,193 and 2,383,319.

In many instances, the components comprising the compositions of the present invention are available as solutions or mixtures in mineral oil or other solvent carriers. The proportion ratios given in this application refer to the active components rather than the mixtures or solutions.

It is preferred that the lubricating compositions of the present invention include at least one detergent in addition to the sulfonates described above. Both the ash-containing detergents, such as the conventional metal based detergents, and the ashless detergents are suitable for use. However, it is preferred to use the ashless detergents in the compositions of the present invention. When these detergents are included in the compositions of this invention, they comprise from about 1% to about 6% by weight of the total composition.

In general, the ashless detergents preferred for use are compounds which comprise an oil solubilizing tail and a polar detergent head. Many ashless detergents fitting this general description are known to the art and are commercially available. For example, basic polyamines substituted with long chain hydrocarbons having from about 30 to about 250 carbon atoms to provide oleophilic character are suitable for use in the present invention. Specific examples of this type of ashless detergent include the polyamines-polyalkylene alkenyl succinimides in which the alkenyl group contains from about 30 to about 250 carbon atoms, the divalent alkylene radicals, which number from about 2 to about 6, each contain from about 1 to about 3 carbon atoms; and the N-dialkylaminoalkyl alkenyl succinimides in which the alkenyl group contains from about 30 to about 250 carbon atoms and the divalent alkylene radical along with the two alkyl radicals contain a total of less than about 10 carbon atoms. See French Pat. No. 1,265,085 and U.S. Pat. No. 3,018,291, which are hereby incorporated by reference into the present application. The required polarity may be supplied by groups containing, for example, oxygen, sulfur, phosphorous as well as nitrogen and mixtures thereof. For example, an ashless detergent can be derived by reacting a hydrocarbon polymer containing from about 30 to about 250 carbon atoms with P.sub.2 S.sub.5. See U.S. Pat. No. 3,003,964; and British Pat. No. 815,810; also U.S. Pat. Nos. 3,256,189 and 3,256,194, which patents are hereby incorporated by reference into the present application. All of these suitable ashless detergents may be generally characterized as compounds comprising a hydrocarbon portion of sufficient size to render the compound oil soluble and at least one non-metallic polar portion which provides a substantial part of the detergent action.

In addition to the additives already described, lubricating oil compositions contemplated herein may contain other agents such as other detergents, anti-wear agents, antifoam agents, corrosion inhibitors, metal deactivators, pour point depressants, oiliness agents, compounds for enhancing the viscosity index of the lubricating oil, etc.

For example, alkali metal and alkaline earth metal phenates can be incorporated into the compositions of the present invention to provide increased alkalinity to the lubricating oil composition and may be monomeric or polymeric in nature, with the polymeric phenates being preferred. The phenate may be polymerized, for example, by reaction with elemental sulfur to form sulfurized phenates. Other polyphenates, for example, carbon bridged polyphenates, are also suitable for use in the present invention. In order to minimize the deleterious effect that the phenates have on silver engine components, it is preferred that sulfurized phenates containing only mono-sulfide linkages be used when these phenates are used to contribute alkalinity to the compositions of the present invention. The preferred phenates for use in the present invention are the alkaline earth metal, more preferably calcium, phenates.

One method for preparing sulfurized phenates is given in U.S. Pat. No. 2,680,096. This patent also discloses a description of the calcium phenates, both sulfurized and unsulfurized, which are suitable for use in the present invention. The unsulfurized calcium phenates have the following formula;

[(R).sub.b AO].sub.2 Ca

wherein A is an "essentially hydrocarbon" aromatic radical, preferably a benzene radical, R is a cyclic, straight-chained or branched-chained, saturated, essentially hydrocarbon radical having from 4 to 30 carbon atoms, O represents oxygen, b is an integer having a value of 1 to 5. An analogous structural formula for other phenates, i.e., phenates associated with metals other than calcium, can be drawn taking into account the valance state of the metal cation.

Examples of calcium phenates include the calcium salts of octyl phenol, nonyl phenol, dodecyl phenol, tetradecyl phenol, hexadecyl phenol, triacontyl phenol, dioctyl phenol, dinonyl phenol, 2,2'-methylene-bis (4-octyl phenol) and the like.

Chlorinated hydrocarbonaceous components may be incorporated to improve the anti-wear properties of the present compositions, for example, toward bronze. These components may vary widely in structure and composition provided that the chlorine content of these components is at least about 5%, preferably at least about 20%, by weight. Included among the suitable chlorinated components are the chlorinated paraffins (including paraffin wax, kerosene and the like), chlorinated olefins and chlorinated polyolefins, chlorinated cycloaliphatic compounds, chlorinated aromatics (including chlorinated biphenyls and chlorinated naphthenes), chlorinated esters of fatty, naphthenic and resin acids and the like and mixtures thereof which contain less than about 70 carbon atoms per molecule. Of course, more than one chlorinated component may be used in a single composition, and such a composition is within the scope of the present invention. It is preferred to use chlorinated paraffins, chlorinated olefins and polyolefins, chlorinated cycloaliphatic compounds, chlorinated esters of fatty, naphthenic and resin acids and mixtures thereof which contain less than about 70, preferably from about 10 to about 40 carbon atoms per molecule. Still more preferably, chlorinated paraffin containing from about 10 to about 40 carbon atoms per molecule can be used. The chlorinated components useful in the present invention may be prepared in any conventional manner, such as, for example, contacting molecular chlorine with the hydrocarbonaceous material to be chlorinated. By "hydrocarbonaceous material" is meant those materials (e.g., paraffins, waxes, olefins, polyolefins and the like) which are composed mainly of hydrogen and carbon, and include such materials which contain, in addition, minor amounts of substituents, such as oxygen, sulfur, nitrogen, etc., which do not substantially affect their hydrocarbon character. The addition of these chlorinated compounds to the compositions of the present invention gives these compositions an unusually strong ability to impart wear resistance to metals such as bronze.

The lubricating oil compositions of the present invention can be used to lubricate engines, such as, for example, many railroad diesel engines and gas turbine and steam turbine engines. Maintaining (or causing to be maintained) a lubricating amount of the oil compositions of the present invention on engine components, such as bearing surfaces, wrist pin bushings and the like, requiring lubrication results in obtaining substantial benefits from the present invention. In addition, the compositions of the present invention which contain a combination of sulfur-containing compounds and naphthyl amine can be used to lubricate engines in the manner noted above to give longer lubricant life because of the substantially improved oxidation resistance of these compositions.

The following examples illustrate more clearly the compositions of the present invention. However, these illustrations are not to be interpreted as specific limitations on this invention.

EXAMPLES 1 to 3

These examples illustrate the significant and unexpected improvement in oxidation resistance obtained by the compositions of the present invention.

Three lubricating oil compositions were prepared by blending together individual components, noted below, at a slightly elevated temperature, i.e., from about 100.degree.F. to about 130.degree.F., to insure complete mixing. The final compositions were as follows: ##EQU3##

Each of these compositions was tested using a bench procedure known as the Sinclair Railroad Oil Oxidation Test. This procedure has been used to screen railroad diesel lubricating oils for oxidation resistance, and the results of this test give a reasonably true indication of the composition's oxidation properties in engine lubrication service.

This bench test procedure involves bubbling five liters of oxygen per hour through 300 ml. of test oil at 285.degree.F. in the presence of a 1 in. by 3 in. steel backed copper-lead specimen. Fifty ml. samples of the oil composition are withdrawn at 48 hour intervals with fresh oil being added to maintain a volume of 300 ml. The test is run for a total of 144 hours at which time the viscosity and percent n-pentane insolubles of the used oil are determined. Each of these determinations give an indication of the extent of oxidative deterioration experienced by the oil during the test period. For example, both the viscosity increase of the test oil over the test period and the amount of n-pentane insolubles in the used oil are indications of the extent to which the oils have experienced chemical reaction involving oxygen, e.g., polymerization, during the test period.

The results of these oxidation tests are as follows:

PROPERTY Examples 1 2 3 ______________________________________ Viscosity, SUS at 100.degree.F. New Oil 994.6 994.6 994.6 Used Oil 2361 2099 1783 %Viscosity Increase 137 111 79.3 n-Pentane Insolubles, Wt.% of Used Oil 3.69 3.24 2.06 ______________________________________

The lubricating oil compositions containing either only the sulfur-containing component (Example 1) or the sulfur-containing component and a diamine component alone (Example 2) experienced substantially higher viscosity increases and n-pentane insoluble production over the test period than did the composition containing the combination of the sulfur-containing component and naphthyl amine (Example 3).

EXAMPLES 4 to 6

These examples further illustrate the improved oxidation resistance of the compositions of the present invention.

Three lubricating compositions were prepared in a manner similar to the compositions of Examples 1 and 2. These compositions were as follows:

Wt.% Example 4 Example 5 Example 6 ______________________________________ Mineral Oil, 160 SUS at 100.degree.F..sup.(7) 99.9 99.5 99.4 Sulfur-Containing Component.sup.(8) 0.1 -- 0.1 Phenyl .alpha.-Naphthyl Amine -- 0.5 0.5 ______________________________________ .sup.(7) Contains 0.1% by weight each of both tetra propenyl succinic anhydride and lauryl oxyacetic acid as rust inhibitors and 0.001% by weight of a conventional silicone anti-foam agent. .sup.(8) Same as (5) in the compositions of Examples 1 and 2.

The oxidation stability of these three lubricating compositions was tested by the following procedure. This procedure is presented in detail in a paper by T. S. Chao, M Kjonaas and B. C. Vitchus entitled "Oxygen Adsorption Test for Evaluation of Oxidation Stability of Lubricating Oils". This paper was presented before the National Combined Fuels and Lubricants and Transportation Meetings of the Society of Automotive Engineers in Philadelphia, Pennsylvania, Nov. 4-6, 1970. This procedure is known to give results which may be reasonably correlated with the true oxidation stability of lubricating oils.

In brief, the above test procedure involves the circulation of oxygen in a closed system through a definite quantity of oil at a controlled temperature and flow rate until a definite volume of O.sub.2 is consumed. Oxygen is circulated through this closed system by means of a tubing pump. As O.sub.2 is being consumed, the pressure in the system drops. This pressure drop which is directly proportional to the volume of O.sub.2 adsorbed by the oil is monitored by a pressure transducer. A potentiometer recorder plots a curve relating the volume of O.sub.2 adsorbed with time.

The test apparatus involves three basic parts. The first part is an oxidation cell which includes a pyrex test tube and a thermocouple well extending to the bottom of the test tube. The test tube is fitted with a gas inlet tube equipped with a three-way stopcock and extending also to the bottom of the test tube. The three-way stopcock permits the feeding of a sample at the beginning of the test from a funnel. The cell may be inserted in an electrically heated aluminum block packed with insulation in a stainless steel beaker. The temperature of the aluminum block may be controlled by a temperature controller through a thermocouple placed in a well drilled in the block.

The second part of the test apparatus is a gas purification train. Oxygen, after bubbling through the oil, carrys with it oil fumes, CO.sub.2, water, and other volatile oxidation products. This material is circulated through various purification equipment by means of a tubing pump. Most of the liquids and condensable products are returned to the oil phase by means of an air-cooled condenser. A very small portion which passes through the condenser is absorbed by conventional means such as active charcoal in an adsorption tube. Water vapor, CO.sub.2 and other acidic gases may be removed by Drierite and Ascarite. Organic materials and CO, if any, are converted in a catalytic tube furnace into H.sub.2 O and CO.sub.2 which are removed by Drierite and Ascarite in another adsorption tube. The gas stream which then contains only unused O.sub.2 is recirculated through the oil. Any O.sub.2 consumed through the cycle is replenished with fresh O.sub.2 from an O.sub.2 source.

The third part of the test apparatus is the O.sub.2 source and measuring device. The oxygen storage tanks connect to the inlet of the oxidation cell. These tanks also connect to one side of the diaphragm of a D/P transducer. The other side of the diaphragm is connected to an enclosed space of about 600 ml. which is used as the reference side. The system is balanced initially by opening a by-pass valve across the diaphragm allowing O.sub.2 to feed into the reference cell. When the test starts, the by-pass valve is closed. Any loss of O.sub.2 in the operating side will move the diaphragm and will generate a potential difference which will be indicated by a recorder which can be calibrated to record directly any loss of O.sub.2 from the system.

In performing the oxidation test, 75 grams of oil composition to be tested were used in the oxidation cell and the oil temperature was maintained at 350.degree.F. until 1300 ml. of 0.sub.2 (measured at 78.degree. .+-. 2.degree.F. and 1 atmosphere) was absorbed. A catalyst mixture was prepared from copper naphtheneate, iron naphthenate, lead naphthenate and a light base oil (150 SUS at 100.degree.F., solvent treated neutral), such that 0.16% by weight of this mixture furnished 24 ppm. each of copper, iron and lead. The catalyst mixture was added to the oil sample before the test, care being taken to have adequate mixing and to avoid oxidation, during mixing. The aluminum block was heated to the operating temperature and the apparatus was evacuated to remove all the air. With the by-pass valve across the transducer open, oxygen was fed into the evacuated system and the tubing pump was turned on to insure adequate circulation. This procedure was repeated twice more. After the third evacuation, the sample was fed into the oxidation cell through the heating funnel and the three-way stopcock. After pressuring the system with oxygen to approximately atmospheric pressure, the pump was turned on and the rate of oxygen flow was adjusted to 1 Ft..sup.3 per hour. The by-pass valve across the transducer was closed and the test was begun.

After a predetermined amount of oxygen had been absorbed into the oil, e.g., 1300 ml., the test was ended. The time required to absorb a given amount of oxygen is a measure of the oxidation stability of the composition being tested. Oxidation stability increases as time required to absorb a given volume of oxygen increases.

Results of these tests were as follows:

Example 4 Example 5 Example 6 ______________________________________ Time required to absorb 1300 ml. of oxygen, minutes 56.9 144.6 972 ______________________________________

These data clearly demonstrate that the compositions of the present invention containing both sulfur-containing components and naphthylamines have unexpectedly improved oxidation resistance relative to compositions containing only one of these materials.

While this invention has been described with respect to various specific examples and embodiments, it is to be understood that the invention is not limited thereto and that it can be variously practiced within the scope of the following claims.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A lubricating oil composition comprising a major proportion of mineral oil of lubricating viscosity; at least one sulfur-containing compound having the following structure; ##EQU4## wherein each R.sup.1 is a monovalent hydrocarbon radical containing from 1 to about 30 carbon atoms, x and y are each integers from 1 to about 9, the sum of x and y being at least 2; and at least one napthyl amine having the following structure; ##SPC3##

wherein R.sup.2 is selected from the group consisting of hydrogen and monovalent hydrocarbon radicals containing from 1 to about 30 carbon atoms, a is an integer from zero to 7 and D is a monovalent hydrocarbon radical containing from 1 to about 30 carbon atoms, said sulfur-containing compound and said naphthyl amine each being present in an amount sufficient to improve the resistance to oxidation of said lubricating oil composition.

2. The composition of claim 1 wherein said sulfur-containing compound is present in an amount from about 0.005% to about 10.0% by weight of the total composition and said naphthyl amine is present in an amount of at least about 0.05% by weight of the total composition.

3. The composition of claim 2 wherein each R.sup.1 contains from 1 to about 18 carbon atoms, R.sup.2 contains from about 6 to about 18 carbon atoms, a is an integer from 0 to 1 inclusive and D contains from about 1 to 18 carbon atoms.

4. The composition of claim 3 wherein said naphthyl amine is present in an amount from about 0.05% to about 2% by weight of the total composition.

5. The composition of claim 4 wherein said sulfur-containing compound is present in an amount from about 0.005% to about 2.0% by weight of the total composition and said naphthyl amine is present in an amount from about 0.1% to about 1.0% by weight of the total composition.

6. The composition of claim 5 wherein each R.sup.1 is independently selected from the group consisting of alkyl, aralkyl and alkaryl containing up to about 18 carbon atoms and x and y are integers from 1 to 3.

7. The composition of claim 6 wherein said naphthyl amine is phenyl alpha naphthylamine.

8. The composition of claim 7 wherein each R.sup.1 is independently selected from the group consisting of alkyl containing from 1 to about 18 carbon atoms.

9. In a method for lubricating an engine comprising components requiring lubrication, the improvement which comprises maintaining a lubricating amount of the composition of claim 1 on the components of said engine requiring lubrication.

10. In a method for lubricating an engine comprising components requiring lubrication, the improvement which comprises maintaining a lubricating amount of the composition of claim 2 on the components of said engine requiring lubrication.

11. In a method for lubricating an engine comprising components requiring lubrication, the improvement which comprises maintaining a lubricating amount of the composition of claim 5 on the components of said engine requiring lubrication.

12. In a method for lubricating an engine comprising components requiring lubrication, the improvement which comprises maintaining a lubricating amount of the composition of claim 6 on the components of said engine requiring lubrication.

13. In a method for lubricating an engine comprising components requiring lubrication, the improvement which comprises maintaining a lubricating amount of the composition of claim 7 on the components of said engine requiring lubrication.

14. In a method for lubricating an engine comprising components requiring lubrication, the improvement which comprises maintaining a lubricating amount of the composition of claim 8 on the components of said engine requiring lubrication.

15. In a method for lubricating a turbine engine comprising components requiring lubrication, the improvement which comprises maintaining a lubricating amount of the composition of claim 7 on the components of said turbine engine requiring lubrication.

16. In a method for lubricating a turbine engine comprising components requiring lubrication, the improvement which comprises maintaining a lubricating amount of the composition of claim 8 on the components of said turbine engine requiring lubrication.