US2897152A

US2897152A - Lubricating oils

Info

Publication number: US2897152A
Application number: US643544A
Authority: US
Inventors: Elliott John Scotchford; Edwards Eric Descamp
Original assignee: CC Wakefield and Co Ltd
Current assignee: CC Wakefield and Co Ltd
Priority date: 1956-03-08
Filing date: 1957-03-04
Publication date: 1959-07-28
Anticipated expiration: 1976-07-28
Also published as: NL100694C; BE555611A; FR1172864A; GB797316A

Description

United States Patent i R 2,897,152 1 LUBRICATING OILS 11 Claims. 01. 252-415 This invention is for improvementsinor relatingv to lubricating oils and is particularly concerned with lubri- 2,897,152 Patented July- 28,

ice.

should not interfere in any way with the normal functions of the two foregoing classes of additive. Many turbine oils, especially marine turbine oils used by the Admiralty, are controlled as regards oxidation stability,

salt water corrosion of ferrous metals,- demulsification value and corrosive action on cuprous metals, by a very rigid specification. It is necessary, therefore, that extreme pressure additives incorporated therein should not adversely alfect compliance with its clauses.

Many of the more commonly employed extreme pres sure additives are detrimental in one or more respects. Thus chlorine compounds generally tend to promote oxe idation and are also prone to hydrolysis with the subeating oils which are to be usedunder conditions which tend to disrupt the lubricant film, which disruption'more particularly takes place'when the pressure between the bearing surfaces is very great. There have already been provided lubricants which have a'high load-carrying capacity. Such lubricants are generally known in the trade as extreme pressure lubricants.

A large number of organic compounds have been pro posed for use as extreme pressure agents, including var ious types of organic diand polysulphides, and the cor responding derivatives of selenium. While the higher polysulphides are very effective in increasing-the film rupture strength of the oil in which they are'dissolved, they tend to be inherently unstable, corrosive', especia1ly to copper and cuprous materials and to exert a pro oxidant efiect on the oil. The disulphides, on the other hand, and other sulphur compounds containing relatively firmly-bound sulphur, though comparatively non-corrosive to copper, usually possess rather poor. extreme'presv sure properties insuflicient to warranttheir use-except in conjunction with other extreme as organic halogen compounds; compounds there have beendisclosed as additives for lubricating oils various simple alkyl and aryl -thiocarbonates and thiocarbamates.

pressure additives such Among this class of It is a nobject of the present invention toprovide lubricating compositions having extreme pressure properties containing additives which are considerably less corrosive to copper and cuprous materials than many known extreme pressure agents of comparable loadcarrying ability. h

It is a further object of the invention to provide lubricating compositions having improved resistance to oxida tion and foam-forming. i

It is yet a further object of the inventionto provide sequent liberation of hydrochloric acid which accelerates rusting of ferrous'metal parts. 1

Many sulphur compounds are also pro 0xidant,-and those which are without effect in this respect usually possessinadequate extreme pressure properties.

We have found a class of organic sulphur compounds which possess surprisingly effective extreme-pressure properties and which at the same time have valuable anti: oxidant properties and foam-inhibiting properties, which are relatively inactive towards copper and cuprous metals and which "do not increase ferrous metal corrosion or emulsification in the presence of water.

According to the present invention there is provided alubricating composition comprising a mineral lubricating oil base and a minor proportion of a compound having the formulaz' 1 e i 1.

N. -s-R.oooR, v Rf v where R and R are alkyl, aryl, cycloalkyl radicals or where R and R are hydrocarbon radicals, preferably CH and R is an alkyl, aryl or cycloalkyl radical. 7.

It is necessary to select R R d R so thatlthe resulting product is oil-soluble in the proportions in which it is to be employed. Preferably R is CH;.;- and R R and R are alkyl radicals, the sum of'the carbon atoms in R R and R being at least six.

additives for turbine oils capable of increasing substantially their load-carrying capacity without at the same time increasing their tendency to oxodise or emulsify with water. I

Thus at the present time many oils used for turbine lubrication consist of specially selected mineraloil blends stabilised against oxidation by the incorporation of antioxidant additives and containing also additives designed to protect ferrous metal parts against rusting or corrosion by, e.g. sea water. 'It is of course important that additional additives, incorporated in such oils tor the purpose of enhancing their extreme pressure properties,

If desired the radicals R R or R may contain halogen substituents, but when the additives are to be employed in turbine oils, the presence of halogen is to be avoided.

It would appear that the presence of ester groups situated in the alpha position to the dithiocarbamate group exerts an activating influence with the consequent pro-. duction of extreme pressure properties substantially in excess of those obtainable by the use of the simple aliphatic or aromatic dithiocarbamates.

Examples ofsuitable compounds falling 'within'i'the above formula include: n-Butyl (dimethyl dithiocarbamyl) acetate, n-Butyl (di-n butyl dithiocarbamyl) acetate, n-Butyl (di isopro'pyl dithiocarbamyl) acetate,

Isopropyl (di-n-butyl dithiocarbamyl) acetate, Z-ethyl hexyl (cyclopentamethylene dithiocarbamyl) acetate CHrCHg S N.CSCHr-OOOCHifilH-CHICHZCH CH;

CHr-C g C2115 10 percent may be employed, but in general from about 0.5 percent to about 2.0 percent is contemplated, especially for use in turbine oils. When it is desired merely to impart antioxidant properties to an oil, smaller proportions of the additives may be employed, e.g. from 0.05 to 0.5. In a preferred form of the present invention the addi tives may be employed in steam turbine oils, especially in marine turbine oils. v i The turbine oils to which the additives of the present invention may be added may contain additional antioxidant additives which maybe of the alkylated phenol type, e.g. tertiary butyl cresol, 2:4 dimethyl-6-tertiary butyl phenol or 2:6 di-tertiary butyl-p-cresol, and will also normally contain antirusting additives which may be of various types, one such class of additives being the acid esters of the long chain mono-esters of polyhydric alcohols described in British patent specification No. 643,025. V

7 When the lubricants of the present invention are to be employed at relatively high temperatures it is desirable to include therein a copper-staining inhibitor. Thus there may be included in the lubricant a minor proportion of a mercapto-arylene-thiazole or a derivative thereof, or an alkyl thiuram disulphide, or an additive or combination of additives of the type disclosed in United States patent application Serial No. 507,147, now US. Patent No. 2,836,561. The copper-staining inhibitor is a cyclic compound capable of homolytic dissociation into free radicals A preferred subclass of inhibitors of this type are 2-mercaptobenzothiazole and its derivatives such as benzothiazole disulphide, hydroxy methyl thiobenzothiazole .and triphenyl methyl thiobenzothiazole, but the corresponding derivatives of other Z-mercaptothiazoles may be employed, all as disclosed in my aforementioned application Serial No. 507,147.

The additives of the present invention may, if desired, be employed in conjunction with organic halogenated compounds in mineral lubricating oils to provide, for example, extreme pressure lubricants for hypoid gears. An example of a suitable organic halogenated compound is chlorinated parafiin wax which may be employed in an amount from 1 to 15% by Weight. Oils containing such combinations of additives are capable of withstanding higher loads than oils which contain only the sulphur compound. As already stated, however, the presence of halogen compounds in turbine oils is undesirable.

" 'Specific examples of lubricating compositions prepared in accordance with the present invention are:

EXAMPLE 1 I A turbine oil having enhanced load-carrying capacity at 140 F. t

and complying with British Admiralty Specifications OM. 100 was prepared, consisting of approximately:

% of a mineral oil having a viscosity of about 170 seconds Redwood at 140 F.

25% of a solvent refined mineral oil having a viscosity of about 65 seconds Redwood at 140 F.

to which was added- 1.5% n-butyl (dimethyl dithiocarbamyl) acetate 0.015% alkylated succinic acid type ferrous metal corrosion inhibitor 0.001% calcium petroleum sulphonate EXAMPLE 2 A turbine oil having excellent oxidation resistance and resistance. to corrosion of ferrous metals in the presence of salt watervconsisted of:

59% of a highly. refined mineral oil having a viscosity of about 65 seconds Redwood at 140 F.

41% of a highly refined mineral oil having a viscosity of about 170 seconds Redwood at 140 F. i

to which blend was added- 0.1% n-butyl (dimethyl dithiocarbamyl) acetate 0.01% of an alkylated succinic acid type ferrous metal .corrosion inhibitor 0.001% calcium petroleum sulphonate This blend had a viscosity of about seconds Redwood EXAMPLE 3 An extreme pressure hypoid rearv axle lubricant, conforming to the Society of Automotive Engineers (SAE) classification grade 140, had the following approximate Composition: v i

75 conventionally-refined Mid-Continent oil of viscosity about 750 seconds Redwood at F.

15 1 solvent refined mineral oil of viscosity seconds Redwood'at 140 F.

8% chlorinated parafi'in wax (approx. 40% chlorine) 2%n-butyl (di-n-butyl dithiocarbamyl) acetate EXAMPLE 4 goodresistance to oxidation and corrosion of ferrous metals in presence of salt water, good resistance to foam ingand improved resistance to the corrosion of copper andicuprous metalsat elevated temperatures, consisted of the composition of Example 1, to which was added- 0.1% -benzothiazole disulphide 0.1% zinc di-n-butyl dithiocarbamate The preparation of n'-butyl (dimethyl dithiocarbamyl) acetate 1s Illustrative of the general method of preparing the compounds of the present invention.

Preparation of n-bzttyl (dimethyl dithiocarbamyl) acetate To a solution of 279 grams (1.85 mols) of n-butyl monochloracetate in an equal volume of alcohol was added very slowly with vigorous stirring at room temperature-940 mls. (2.3mols) of 30.9% w./w. aqueous solution of'sodi-umdim'ethyl dithiocarbamate expanded with an'equal volume of alcohol An exothermic reaction-took'place and sodium chloride separated together with a heavy oily liquid. The reaction was completed by warming the mixture to 70" C. Distilled water was now added to dissolve the sodium chloride, andthe product, which crystallised on standing and scratching, was filtered, off. H a i v I I';' Ihe yield was 375 grams (87% oftheoretical). M.P 30 C; after. recrystallisation from, petroleum ether.

llercentsa -7-2; h p c' 7 Other esters prepared from the corresponding ch1orace-;.

tates and sodium dithiocarbamates included: Ethyl" (dimethyl dithiocarbamyl) acetate, crystalline solid, MP. 61 C.

with a rubbing ratio of 3.4 to 1, loading being applied manually in incrementsv of 5. lb. (scalereading) every seconds until failure took place.

The additives were dissolved in a mineral oil blend such as Oil B which consisted of 80% of a solvent-re- 0 r0 dimeth 1 dithiocarbaml acetate solid er- I Is g 2(86; thegretical, 28.9% n (p 5 guild mniieral oil havmg a viscosity of about 150 seconds Isobu 1 dm eth l dithiocarbam l acetate .0 stalline 6 9 140 i of solvent'refined g y y) I W eral 011 having a viscosity of about seconds Redwood 140 F. Iso r0 1 di-n-bu 1 dithiocarbam l acetate, low meltat ty I .0 y A very similar base oil, 011 A, consisted of the two mg sohd (percent N, 4.34, theoretical, 4.74) 10 a1 H d d n-Butyl (di-n-butyl dith'ioca'rbamyl) acetate, light amber mmer 0 e m Example 1 m -20 F liquid (percent S, 203; thematica1,v 201) had a viscosity index of about 60 whereas 011 B =had a 2-ethyl hexyl (cyclopentamethylene dithiocarbamyl) acevlscosltymfdex 01595-- l I tate, amber oil, t S, 16 0;theoretica1, 19.37) In certain blends marked with an asterisk an alkylated Phenyl '(di-n-butyl dithiocarbamyl') acetate, brown il 5 succinic acid type ferrous metal corrosion inhibitorwas (percent S, 18.2; theoretical, 18.9) I also Present n-Butyl u(dimethyl dithiocarbamyl) isobutyrate (percent The results of load-carrymg tests are summarized in I S, 21.8; theoretical, 24.3) Table 1.

Four-ball machine tests Percent SAE- sulphur SOD Tg3t"'Ba59 provided Load, 1 a Mean wear Mean test No. 011 Additlvespresent. the Kg, at Weld (mms) at Hertz failure additive incipient point, load load seizure Kg. (lbs.)

100 150 Kg. Kg.

'1 None Nil 32/30 2.9 11 as 2 'B n-Butyl (dimethyl dithlocarbamyl) acetate, (0.75%) -1-.- 0. 20 95/100 220 1.9 2.2 41 3 B n-Butyl (dlmethyl' dithiocarbamyl) acetate (1.0%) 0. 26 95/100 210 1,3 22 45 130 A .n-Butyl (dimethyldithiocarbamyl) acetate (l.5%) 0. 39 90/95 190 1. 4v 2.0 "A- 'n-Butyl (di-n-butyldithiocarbamyl) acetate (2.0%)--- 0.40 85/90 200/220 1.9 2.1

B Isopropyl (di-n-butyl dithiocarbamyl) acetate (2.0%)" 0. 40 90/95 230 1. 7' 2.0 B Phenyl (di-nbutyl dithiocarbamyl) acetate (2.15%)--- 0. 40 110 220 0. 5 2.0 B 2-ethyl hexyl (cyclopentamethylene dithiocarbarnyl) acetate (2.5%)- 0. 40 120' 250 0.6 2.0 B n-Butyl a (dlmethyl-dithiocarhamyl) isobutyrate (1.05%) 0.36. 85/130 200 0.0 1.8 B flachloroethyl (di-n-butyl dithiocarbamyl) acetate (2.0%) 0. 40 95/100 230 0.7 1.8 B S-n-hexyldi-n-butyl dithiocarbamate (1.92%). 0. 40 75/80 200 1.8 2.1 13* S-n-hexyl di-n-butyl dithiocarbamate (1.25%)- 0. 20 75/80 2. 0 2. 5 30 120 A Di-benzyl disulphide (1.0%) 0.26 60/70 260 1.0 1.5 135 In an attempt to prepare B-chloroethyl (di-n-b-utyl dithiocarbamyl) acetate from /ihloroethyl monochloracetate and sodium di-n-butyl dithiocarbamate, an amber oil was obtained containing 8.7% Cl (theoretical, 11.1%). This evidently consisted of a mixture of compounds, some of the terminalchlorineatoms having been replaced. 0f the foregoing compounds, the first three listed were not soluble to the extent of 1.0 percent in mineral oil blend A, as used in the majority of the tests herein described.

' T 0 demonstrate the. efie'otiveness of the compounds used in the compositions of the present invention as extreme pressure agents, tests were carried out on the well known four-ball machine similar to that described by Boerlage in .Engineering, 13th July 1933, volume 136, page 46. This apparatus comprised four steel balls arranged in the form of a pyramid.- The top ball was held in a chuck attached to a spindle rotating at approximately 1500 ppm. and pressed against the three bottom balls clamped in a stationary ball holder. The balls were immersed in the oil to be tested. Tests were normally run for one minute at a series of difierent loads, but in certain cases supplementary tests were carried out for a duration of ten seconds, the Mean Hertz Load" being calculated by the standard procedure described in U.S. Federal Specification VV-L-79ld Method 650.3 (1950).

I Certain tests were also carried out on the well known Society of Automotive Engineers (S.A.E.) Testing Machine described by Neely in the Journal of the Society pf. Automotive Engineers, volume 39, page 293 (1936), by a modified procedure known as the S.A.E.S.O.D. test, described byMcTurk in Wright Aeronautical Development Centre (W.A.D .C.) Technical Report 53-88, page (1953), published by the U.S. Department of Commerce, Ofiice of Technical Services. In test pror a s-m9 A- tiw na a r rea t 0. 0 -P-m:

In Table 1 tests '2 to 10 summarize the load-carrying properties of a vairety of lubricating oils prepared in ac cordance with the present invention, from which it will be seen that in all cases the load-carrying'capacity of the base oil (test 1) 'is greatly increased by the presence of organic dithiocarbamyl acetates. Tests 11 and, 12 give comparative figures obtained with a simple conventional organic dithioca-rbamate, while test 13 quotes similar figures for dibenzyl disulphide, a well known extreme pressure additive known to be among the most efiective of the simple organic disulphides.

It will be seen by comparing tests 2, 3, l2 and, 13 that n-butyl (dimethyl dithiocarbamyl) acetate, which is typical of the additives of the present invention, gave significantly better results on the four ball machine than both the conventional dithiocarbamates and dibenzyl disulphide, although the total amounts of added sulphur in the oils were identical in tests 3, l2 and 13 and'less in test 2. In this connection it should be pointed out that the load at the point of incipient seizure and the mean Hertz load are generally believed to be the most sig'nifi cant of the four ball machine test results quoted.

By comparing test 11 with tests 4 to 10 (all about .40% added S) it will again be seen that the simple thiocarbamate ester was inferior to the compounds of the present invention.

When used in turbine oils, the organic dithiocarbamyl acetates not only do not adversely affect the properties of such oils but confer valuable'antioxidant' and antifoaming properties, thus rendering unnecessary the addition of specific antioxidant and antifoaming additives. If special load-carrying properties are not required, quite small amounts of the dithiocarbamyl acetates are sulficient to confer a degree of oxidation, and foaming sta:

im)" a t TABLE 2 Oxidation test Foaming test (76 F.) Acidity (milli- Demul- Acidity Saltwater Test Additive Base grams sificaafter Demulsicorrosion No. oil KOH tion oxidation fication Tendpar value (mgs. value eney Stability (mls.) gram) KOH after oxi- (mls.) per dation gram) 14 None A 0. 06 Failed, unless anti- N o rusting 490 Nil (8 mins). oxidant present. n-Butyl (dimethyl dithiocarbamyl) acetate (1.5%)" A 0.06 0.11 do 10 N11 (10 sees). 16... n-Butyl (dimethyldithiocarbamyl) acetate (0.75%) B 0.11 630 do Nil N 17 n-Butyl (dimethyldithiocarbamyl) acetate (0.1%) A 0.22 110 N11 (2 mins.). 18 n-Bntyl (di-n-butyl dithiocarbamyl) acetate (2.0%). A 0.08 240 No rusting 19.--" n-Butyl (dimethyl dithiocarbamyl) acetate (1.0%), B 0.17 600 do Ni.l'(1.5 mins.).

Benzothiazole disulphide (0.1%). 20.-. As test 19+0.1% zinc di-n-butyl dithiocarbamate B 0. 11 360 do 400 Nil (6 mins.).

Table 2 illustrates the effect of the additives on typ1- temperatures, a selection of the results belng given in cal turbine oils containing rust inhibitors which, with the 20 Table 3.

TABLE 3 [Tests recorded in this table were 24 hours duration, the base oil used throughout being oil B*] Appearance of copper strips atgest Additives present 21 n-Butyl (dimethyl dithiocarbamyl) Light brown/pea- Dark peacock] Dark peacock Dark brown- Dark peacock, acetate (0.75%). cock stain. magenta. brown; 10% black. black patch. at one end. 22 As test No. 21+0.1% benzothiazole Orange brown powdisulphide. dery deposit. 23"--- As test N o. 22+0.1% zinc di-n-butyl Reddish brassy Light golden Patch of yellow Light peacock Powdery light dithiocarbamate. stain. brow-n. deposit. with powdery brown deposit; light brown deposit.

There was no stain of the copper during 3 hours at 100 0. by n-butyl (dimethyl dlthiocarbamyl) acetate in concentrations up to at least 1.5%,

the absence of copper deactivators.

addition of a suitable antioxidant, would comply with British Admiralty Specification O.M. 100.

In test 17 the foaming test was carried out using as base oil the higher viscosity component of oil A without rust inhibitors.

The methods employed for determining the various values quoted above were standard methods described in Standard Methods for Testing Petroleum and its Products, and having the following references:

Acidity I.P. 1/53 Method A (page 12, 1943 edition) Demulsification value I.P. 19/51 (page 117, 1951 edition) Oxidation test I.P. 114/53 P (page 395, 1953 edition) Salt water corrosion test I.P. 135/51 (page 390, 1951 edition) (modified to comply with OM. 100 specification) Foaming stability I.P. 146/55 T (page 266, 1956 edition) (sequence 1 only quoted in the above table) It will be seen from Table 2 that dithiocarbamyl acetates function effectively as antioxidants even in quite low concentrations, thus enabling turbine oils to satisfy the oxidation requirements of QM. 100 specification (0.20 mg. KOH per gram maximum after oxidation test) without the addition of any other oxidation inhibitors.

By comparing tests 15 to 17 and 19 with test 14, it will be seen that they also function effectively as inhibitors of foaming. In test 20, the presence of zinc di-n-butyl dithiocarbamate evidently interfered with this eifect.

Other properties of the oils, such as acidity, demulsification value and salt-water corrosion resistance were unafi'ected by the addition of the dithiocarbamylacetates.

In order to determine the elTect of the lubricating oils of the present invention on copper. at various temperatures, a series of tests were carried out in which strips of clean electrolytic quality copper foil 2 inches long and /2 inch wide were immersed in the oils in test tubes and heated in an oven for various periods of time at different From Table 3 it will be seen that n-butyl'(dimethyl dithiocarbarnyl) acetate, which is typical of the additives of the present invention, is very mild in its action towards copper at temperatures of the order of to C. such as are encountered in steam turbines. Further improvement, particularly at the higher temperatures, may be obtained by including benzothiazole disulphide or a combination of this compound with zinc di-n-lbutyl dithiocarbamate. 1

A turbine oil complying with British Admiralty Specification O.M. 100 and consisting of base oil B containing 1.0% n-butyl (dimethyl dithiocarbamyl) acetate together with rust inhibitors as in Example 1 and copper deactivators as in Example 4 was subjected to a test on the well known Institution of Automobile Engineers (I.A.E.) 3 A" Centres Gear Machine described by Mansion in the Journal of the Institute of Petroleum, volume 38, page 633 (1952). This machine was operated at 4000 rpm. using En. 34 gears, with an oil temperature of 70 C. The average failure load was 93 lbs, a typical 0.M. 100 turbine oil without load-carrying additive failing at 29 lbs.

To,illustrate the use of dithiocanbamyl acetates in extreme pressure lubricants suitable for hypoid gears, the composition of Example 3 was tested on the four ball machine (standard one minute run), the weld point being 490-500 kg. and the mean wear scar diameter at 100, 200, 300 and 400 kg. load being respectively 0.5, 1.2, 1.7 and 2.3 mms.

A commercially available hypoid gear oil having approximately the same viscosity and complyingwith US. Army Specification MILL2105 welded at 400 kg, the mean Wear scar diameter at 100, 200 and 300 kg. load being respectively 0.4, 1.5 and 2.0 ms.

We claim: I 1. A lubricating composition, consisting essentially of a mineral lubricating oil base containing 'from"0;05

percent up to 10 percent by weight of a compound having the formula: 7

where X is selected from the group consisting of R1 and R2 hydrocarbon chain of nitrogen atom so as to form a ring structure, from the group consisting of -CH being lower alkyl radicals, and an aliphatic five carbon atoms attached to the R is selected 8 XNJL-S-RCOOR:

Where X is an aliphatic hydrocarbon chain of five carbon atoms attached to the nitrogen atom so as to form a ring structure, R is selected from the group consisting of 'CH2,

Bui t-H and where R; and R are lower alkyl radicals, and R is selected from the group consisting of a phenyl radical and an alkyl radical containing no more than eight carbon atoms.

4. A lubricating composition as claimed in claim 1, wherein R contains halogen substituents.

5. A lubricating composition consisting essentially of a mineral lubricating oil base containing from 0.05 percent up to 2 percent by weight of n-butyl (dimethyl dithiocarbamyl) acetate.

6. A lubricating composition consisting essentially of "10 a mineral lubricating oil base containing from 0.0519 0.5 percent by weight of a compound having the formula: a. s

N.CS-OHaCO0R| R: where R and R are lower alkyl radicals and R is'au alkyl radical containing not more than eight carbon atoms.

7. A steam turbine oil' consisting essentially of a mineral lubricating oil base containing from 0.5 to 2 percent by weight of a compound having the formula:

5 X'Nlfll-S-RCOOR:

where X is selected from the group consisting of R. R and R being lower alkyl radicals, and an aliphatic hydrocarbon chain of five carbon atoms attached to the nitrogen atom so as to form a ring structure, R is selected from the group consisting of CH where R; and R are lower alkyl radicals, and R is selected from the group consisting of a phenyl radical and an alkyl radical containing no more than eight carbon atoms.

8. A steam turbine oil consisting essentially of a mineral lubricating oil base containing from 0.5 to 2 percent by weight of a compound having the formula:

where R and R are lower alkyl radicals and R is an alkyl radical containing no more than eight carbon atoms.

9. A steam turbine oil as claimed in claim 7, wherein there is included from 0.005 to 0.1 percent by weight of an anti-rusting additive selected from the group consisting of an acid ester of a long-chain monoester of a polyhydric alcohol, and an alkylated succinic acid.

10. A steam turbine oil as claimed in claim 7, wherein there is included from 0.01 to 0.5 percent by weight of a copper-staining inhibitor selected from the group consisting of Z-mercapto benzothiazole and a derivative thereof capable of homolytic dissociation into free radicals 11. A lubricating composition consisting essentially of a mineral lubricating oil base containing from 0.05 percent up to 10 percent by weight of a compound having the formula:

s XNJ'l-S-ILCOOR;

where X is selected from the group consisting of Elli 12 R and R being lower alkyl radicals, and an aliphatic Where R and R 'are lower alkyl radicals, and R is hydrocarbon chain of five carbon atoms attached to selected from the group consisting of a phenyl radical the nitrogen atom so as to form a ring structure, R is and an alkyl radical containing no more than eight selected from the group consisting of -CH carbon atoms, and from 1 to 15 percent by weight of '5 a chlorinated paraflin wax.

R4(|)H v g V References Cited in the file of this patent v UNITED STATES PATENTS L 2,160,851 Faust June 6, 1939 1 2,160,880 Loane June 6, 1939

Claims

1. A LUBRICATING COMPOSITION CONSISTING ESSENTIALLY OF A MINERAL LUBRICATING OIL BSE CONTAINING FROM 0.05 PERCENT UP TO 10 PERCENT BY WEIGHT OF A COMPOUND HAVING THE FORMULA: