US3909420A

US3909420A - Lubricant composition containing thiadiazoles and napthylamines as antioxidants and method of lubrication using said composition

Info

Publication number: US3909420A
Application number: US401093A
Authority: US
Inventors: Byron W Turnquest; Tai S Chao; Victor E Broman
Original assignee: Atlantic Richfield Co
Current assignee: Atlantic Richfield Co
Priority date: 1971-07-09
Filing date: 1973-09-26
Publication date: 1975-09-30
Anticipated expiration: 1992-09-30
Also published as: FR2244813A1; GB1401076A; CA983914A; FR2244813B1; US3775321A; GB1480387A

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.

Description

Uit States Patent Turnquest et al.

[ 1*Sept. 30, 1975 LUBRICANT COMPOSITION CONTAINING TI-IIADIAZOLES AND NAPTHYLAMINES AS ANTIOXIDANTS AND METHOD OF LUBRICATION USING SAID COMPOSITION Inventors: Byron W. Turnquest, Chicago; 'Iai S. Chao, Homewood; Victor E. Broman, Palos Park, all of 111.

Appl. No.: 401,093

Related U.S. Application Data Continuation-impart of Ser. No. 161,947, ScpL 9, 1971, Pat. No. 3,775,321.

US. Cl 252/47; 252/391 Int. Cl. CIOM 1/38 [58] Field of Search 252/47, 391

[56] References Cited UNITED STATES PATENTS 2,009,480 7/1935 Craig 252/401 X 2,719,126 9/1955 Fields et a1. 252/391 X 3,236,774 2/1966 Thompson et a1 252/56 S 3,513,084 5/1970 Breton et al. 252/52 R X 3,663,561 5/1972 Blaha 252/47 3,775,321 11/1973 Turnquest et a1 252/50 Primary ExaminerDelbert E. Gantz Assistant Examiner-Andrew H. Metz Attorney, Agent, or FirmFrank J. Uxa

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

16 Claims, N0 Drawings LUBRICANT COMPOSITION CONTAINING Tl-IIADIAZOLES AND NAPTHYLAMINES AS ANTIOXIDANTS AND METHOD OF LUBRICATION USING SAID COMPOSITION This application is a continuation-in-p'art of application Ser. No. 161,947, filed July 9, 1971 and now US. Pat. No. 3,775,321.

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 presentinvention. 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 wherein each R 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 it has been found that the combination of the sulfurcontaining 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 sulfurcontaining 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 sulfurcontaining 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 100F. 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 100F. 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 still more preferably at least about by weight of the total composition.

The general formula for containing compounds is the suitable sulfurwherein each R 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 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 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 is alkyl having from 1 to about 18 carbon atoms and x and each are integers from 1 to 3. Examples of suitable monovalent hydrocarbon radicals are ethyl, propyl, butyl, hcxyl, octyl, nonyl, decyl, dodecyl, tridecyl, hexadecyl, octadecyl, cyclo-hexyl, phenyl, tolyl, benzyl, naphthyl, styryl and the like. These sulfurcontaining compounds and methods for their preparation are described in US. 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:

wherein R is selected from the group consisting of hydrogen and monovalent essentially hydrocarbon radicals containing from 1 to about 30, preferably from about 6 to ab.) ut 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 substitute'd counterparts of these radicals. Included among the 1 suitable amines are phenyl alphaor betanaphthylamine, octylphenyl alphaor betanaphthylamine, alpha-alpha, alpha-beta or beta-beta dinaphthylamines, various 'phenanthryl-anthyrl naphthylamines, xylyl naphthylamines, dodecyl phenyl naphthylamines, biphenyl naphthylamines and phenyl naphthylamin es alkylated with olefins containing from about 8 to about 24 carbon atoms per molecule. Specific examples of these olefins include pinene, a-methylstyrene, and the like. The naphthylamines in which the essentially hydrocarbon R 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., hydrocarbocompositions of the present invention, it is preferred to include from about 0.1% to about 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.

Sullonates derived from sulfonic acids having about 12 to about 200v carbon atoms per molecule are of particular usefulness. in the present invention. Among these sulfonic acids are monoand polyalkyl substituted naphthalene sulfonic acids, phenol sulfonic acids, diphenyl ether sulfonic acids, diphenyl ether disulfonic acids, diphenyl sulfide-sulfonic acids, di-naphthylsultide-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, monoand 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 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 ashcontaining 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 US. 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 8 See US. Pat. No. 3,003,964; and British Pat. No. 815,810; also US. Pat. Nos. 3,256,189 and 3,256,l94, 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 US. 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;

[( h, 12 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, 0 represents oxygen, b is an integer having a value of l 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 suit able 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 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 illlustrate more clearly the compositions of the present invention. However, these illustrations are not to be interpreted as specific limitations on this invention.

EXAMPLES l 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 F. to about F., to insure complete mixing. The final compositions were as follows:

CUMIUNI l W l.'/!

Example I Example 2 I Example 3 Mineral Oil. 890 SUS at 891 89.0 88.85

100F. Sulfurized Calcium Phcnate 6.0 6.0 6.0 Ashless Detergent 3.0 3.0 3.0 Calcium Sulfonate L7 L7 1.7

Chlorinated Hydrocarbonaceous Component Sulfur-Containing Component"' Phenyl a-Naphthyl Amine Diamine Component "A mixture of about 5071 by weight of active material in a mineral oil carrier. The active material comprises mono-sulfide linked phenate derived from dodecyl phenol. The mixture has a total hasenumber (ASTM Test D 664) of about 85. *A mixture of about 50% by weight of detergent in a mineral carrier. The detergent comprises. as an oil solubilizing ortion, a hydrocarbon olefin polymer which is believed to contain an average of about 75 to about 100 carbon atoms and. to provide a substantial part of the detergency action. a polar portion containing basic nitrogen. This detergent hasna molecular weight of about 7860. This commercially available detergent mixture contains about L571 by weight of nitrogen and has a total base number of from about 30 to about 40. ""A mixture of about 45% by weight of active calcium sulfonate in a mineral oil carrier. The calcium sulfonate is derived from petroleum sources and has about carbon atoms per molecule. 'A chlorinated hydrocarbon paraffin containing about l2 carbon atoms per molecule and about 60% by weight of chlorine. 'Comprising primarily:

I a I u CH CH CH -CH CllNH CH2 NH(|ZH-CH2-CH;, CH CH Each of these compositions was tested using a bench duction over the test period than did the composition procedure known as the Sinclair Railroad Oil Oxidacontaining the combination of the sulfur-containing tion Test. This procedure has been used to screen railcomponent and naphthyl amine (Example 3). road-diesel lubricating oils for oxidation resistance, and

the results of this test give a reasonably true indication EXAMPLES 4 to 6 of the com positions oxidation properties in engine lu- These examples further illustrate the improved oxibrication scrvice. dation resistance of the compositions of the present in- .This bench test procedure involves bubbling five livention.

ters of oxygen per hour through 300 ml. of test Oil a Three lubricating compositions were prepared in a 285F. in the presence of a l in. by 3 in. Stee acked manner similar to the compositions of Examples 1 and copper-lead specimen. Fifty ml. samples of the oil com- 2 Th compositions were as f ll position are withdrawn at 48 hour intervals with fresh oil being added to maintain a volume of 300 m]. The

test is run for a total of 144 hours at which time the vis- 4 cosity and percent n-pentane insolubles of the used oil Example 4 Example 5 Example 6 are determined. Each of these determinations give an Mineral Oil, 160 sus m indication of the extent of oxidative deterioration expekfggs z rienced by the oil during the test period. For example, c 0,] both the viscosity increase of the test oil over the test Pheny} p y period and the amount of n-pentane insolubles in the Amme used are indications Of the extent to the oils "'Contains 0.1; by weight each of both tetra propenyl succinic anhydride and have experienced che reaction involving yg rust inhibitors and 0.001% by weight of a conventional e olymerization during the test period ""Same as (5) in the compositions of Examples l and 2.

The results of these oxidation tests are as follows:

The oxidation stability of these three lubricating compositions was tested by the following procedure.

PROPERTY Exazmples 3 This procedure is presented in detail in a paper by T.

S. Chao, M Kjonaas and B. C. Vitchus entitled Oxy- Viscosity, SUS at 100F. gen Adsorption Test for Evaluation of Oxidation Stabil- New Oil 994.6 994.6 994.6 Used on 2361 2099 783 ity of Lubricating Oils This paper was presented be %Viscosity Increase 137 ll] 79.3 fore the National Combined Fuels and Lubricants and n-Pentane lnsolubles,

w [7 f U d 01 3 69 3 24 2 06 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 The lubricating oil compositions containing either stability of lubricating oils. only the sulfur-containing component (Example 1 or In brief, the above test procedure involves the circuthe sulfur-containing component and a diamine comlation of oxygen in a closed system through a definite ponent alone (Example 2) experienced substantially quantity of oil at a controlled temperature and flow higher viscosity increases and n-pentane insoluble prorate until a definite volume of O is consumed. Oxygen is circulated through this closed system by means of a tubing pump. As O is being consumed, the pressure in the system drops. This pressure drop which is directly proportional to the volume of O adsorbed by the oil is monitored by a pressure transducer. A potentiometer recorder plots a curve relating the volume of 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 tempera ture 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 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 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 0 and CO which are removed by Drierite and Ascarite in another adsorption tube. The gas stream which then contains only unused O is recirculated through the oil. Any O consumed through the cycle is replenished with fresh 0 from an O source.

The third part of the test apparatus is the 0 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 to feed into the reference cell. When the test starts, the by-pass valve is closed. Any loss of O 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 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 350F. until 1300 ml. of 0 (measured at 78 i 2F. and l atmosphere) was absorbed. A catalyst mixture was prepared from copper naphtheneate, iron naphthenate, lead naphthenate and a light base oil (150 SUS at lO0F., 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 threeway 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 l Ft. 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:

These data clearly demonstrate that the compositions of the present invention containing both sulfurcontaining 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.

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;

wherein each R 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;

(Dla

the resistance to oxidation of said lubricating oil composition.

2. The composition of claim 1 wherein said sulfurcontaining 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 contains from 1 to about 18 carbon atoms, R contains from about 6 to about 18 carbon atoms, a is an integer from to l 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 sulfurcontaining 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 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 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.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3,909,420

DATED Septenber 30, 1975 INVENTOR(S) Byron W. Tirmquest et al It is certified that error appears in the above-identitied patent and that said Letters Patent are hereby corrected as shown below:

On the Title Pa e lst oolmnn, line 63; delete the word "Sept." and substitute therefore July--.

Signed and Sealed this twenty-third D ay of December 1 9 75 [SEAL] A ttes t:

RUTH C. MASON Commissioner nfPa rents and Trademarks UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 1 3,909,420

DATED September 30, 1975 INVENTOR(S) Byron W. Turnquest et al It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

On the Title Page lst column, line 63; delete the word "Sept." and substitute therefore July-.

Signed and Scaled this twenty-third a O [SEAL] D y fDecember1975 A ttest:

RUTH C. MASON C. MARSHALL DANN Attestmg Officer Commissioner ofParents and Trademarks

Claims

1. A LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PROPORTION OF MINERAL OIL OF LUBRICATING VISCOSITY AT LEAST ONE SULFURCONTAINING COMPOUND HAVING THE FOLLOWING STRUCTURE,

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 R1 contains from 1 to about 18 carbon atoms, R2 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.

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 R1 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.

8. The composition of claim 7 wherein each R1 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.