CA1047477A

CA1047477A - Turbine oil compositions

Info

Publication number: CA1047477A
Application number: CA225,814A
Authority: CA
Inventors: Albert M. Durr (Jr.); Robert A. Krenowicz
Original assignee: Continental Oil Co
Current assignee: ConocoPhillips Co
Priority date: 1974-10-07
Filing date: 1975-04-24
Publication date: 1979-01-30
Also published as: US3923672A

Abstract

Turbine Oil Compositions Abstract of Disclosure A lubricating oil composition, particularly suitable for use in steam turbines or gas turbines, is disclosed. The turbine oil composition comprises a major amount of a mineral or synthetic hydrocarbon base oil and an effective amount of a combination of the following materials: triphenyl phosphite or a trialkyl-substituted phenyl phosphite; diphenylamine or alkylated diphenylamine;
phenyl .alpha.-naphthylamine, phenyl .beta.-naphthylamine, alkyl or alkaryl substituted phenyl .alpha.-naphthylamine, or alkyl or alkaryl substituted phenyl .beta.-naphthylamine; benzotriazole or alkyl-substituted benzotriazole; partial ester of alkyl or alkenyl succinic anhydride. In a preferred aspect, the turbine oil composition contains additionally an effective amount of a copolymer of N-vinyl-2-pyrrolidone and an .alpha.-olefin.

Description

: 10~7477 . .
Background Field of the Invention The invention is in the field of lubricating oils which are particularly suitable for use in gas turbine engines, including aircraft and automotive, and stationary steam tur~ine engines.
General Back~round It is generally recognized that the operating ; conditions of gas turbine engines expose the lubricant to extreme conditions. In order to be satisfactory, the lubricant must be resistant to oxidation and corrosion at high temperatures. Moreover, the lubricant must be resistant to deposit-formation at high temperatures.
Normally, gas turbine and steam turbine units require different lubricant types, the former synthetic ester-based oils and the latter petroleum oils.
We have found a particular combination of lubri-cant additives which work in mineral lubricating oils or synthetic hydrocarbon lubricating oils. Furthermore, the lubricant compositions of our invention work in either steam turbines or gas turbines. They are particularly suitable for use in gas turbines. Because of this, our lubricant compositions provide an important advance in the art.
Prior Art ~ach of the lubricant additives used in our lubricant compositions is known to be useful in lubricating oils. However, we have found that certain synergistic relationships are present in the additives which provide improved results in the combinations used. For example, we

-2-~' :

~047477 have found that the lubricant compositions of the broad .~ . .
aspect of our invention provide superior performance, particularly when compared to commercially available prod-ucts. While these compositions provide good overall test - s results, we have found that the addition of a small amount of the particular copolymer used in our invention provides a : .
pronounced improvement in the test results.
srief Summary_of the Invention Broadly stated, the present invention is directed to a lubricating oil composition which comprises a major amount of a mineral or synthetic hydrocarbon base oil and an effective amount of a combination of the following : materials: triphenyl phosphite or a trialkyl-substituted phenyl phosphite; diphenylamine or alkylated diphenylamine;
phenyl -naphthylamine, phenyl ~-naphthylamine, alkyl or alkaryl substituted phenyl ~-naphthylamine, or alkyl or alkaryl substituted phenyl ~-naphthylamine; benzotriazole or alkyl-substituted benzotriazole, partial ester of alkyl or alkenyl succinic anhydride.
In a preferred aspect, the lubricating oil com-position contains additionally an effective amount of a copolymer of N-vinyl-2-pyrrolidone and an -olefin.
The lubricating oil compositions of our invention have properties which render them particularly useful in steam or gas turbines.
Materials Used -- .
The base oil can be a conventionally refined m neral lubricating oil or a synthetic hydrocarbon lubri-cating oil. The mineral lubricating oils are well known to those skilled in the art. Both light viscosity (e.g., pale ~i iO47477 -~ oils) and heavy viscosity (e.g., bright stock) oils can be used. A complete description of mineral lubricating oils .,.
is provided by Nelson's "Petroleum Refinery Engineering"
(McGraw-Hill, New York, 1958).
Suitable synthetic hydrocarbon lubricating oils include di-n-long-chain alkaryls, as described herelnafter, linear mono-olefin oligomers, and a composition consisting essentially of di-n-long-chain alkaryls and trialkyl-substituted tetrahydronaphthalenes.
- 10 Linear mono-olefin oligomers, which are suitable - as lubricating oils, are described in several U.S. patents, e.g., U.S. 3,382,291, U.S. 3,149,178, and U.S. 3,808,134.
A particularly suitable linear mono-olefin oligomer composition is prepared from -olefins containing 6 to 16 carbon atoms, more suitably 8 to 12 carbon atoms, and preferably 10 carbon atoms. The linear mono-olefin oligomer composition contains at least 50 weight percent, more usually at least 60 weight percent, of materials containing 24 to 60 carbon atoms.
The term di-n-long-chain alkaryl refers to materials represented by the formula R ~ A

l~L 1 wherein R and Rl are alkyl groups containing from 6 to 18 i 25 carbon atoms, more suitably from about 9 to about 15 carbon atoms, and preferably from about 10 to 14 carbon atoms, with the sum of R and Rl being from about 20 to about 28 carbon atoms and wherein A and Al are hydrogen or a Cl or C~ alkyl group, but preferably are hydrogen.
Thus, the preferred di-n-long-chain alkaryl is a ~0~7477 di-n-alkylbenzene wherein the alkyl group contains from about 10 to about 14 carbon atoms.
The alkyl groups are substantially straight-chain (thus the term n-alkaryls) wherein, preferably, at least 95 percent of the alkyl substituents are bonded to the benzene nucleus through a secondary carbon atom of the respective alkyl groups. While we prefer the term "n-alkaryls," other terms such as linear alkaryls or straight-chain alkaryls - are equally descriptive.
A particularly suitable di-n-long-chain alkaryl--trialkyl-substituted tetrahydronaphthalene composition typically contains the following Component: Percent by Weight Di-n-long-chain alkaryls61-92 Trialkyl-substituted tetrahydro-naphthalenes 5-30 Miscellaneous alkyl aromatics:
Less than lS
Preferably less than 10 The composition is also characterized as having - the following properties:
Viscosity index 80-116 ~- Pour Point, F -40 to -80 Molecular weight range 350-526 Preferably 375-480 The di-n-long-chain alkaryls meet the description provided in the foregoing.
The trialkyl-substituted tetrahydronaphthalenes can be represented by the formula , .

:

:

H R

wherein Rl and R2 contain from 1 to about 13 carbon atoms each, with the sum of Rl and R2 being from about 6 to about 14 and R3 and R4 contain from 1 to about 16 carbon atoms with the sum of R3 and R4 being from about 9 to about 17. The alkyl groups, Rl, R2, R3, and R4, are straight-chain.
The trialkyl-substituted tetrahydronaphthalenes have the same boiling range as the di-n-alkylbenzenes. In addition, they have approximately the same molecular weight.
Suitable phosphites include triphenyl phosphite and trialkyl-substituted phenyl phosphites, wherein the phenyl moiety has 1 or 2 alkyl substituents, each of which contains 1 to 12 carbon atoms. Examples of the latter-: named phosphites which are suitable include triphenyl phosphite, tritolyl phosphite, tricresyl phosphite, tri-; hexylphenyl phosphite, tributylphenyl phosphite, and tri (mixed mono- and dinonylphenyl) phosphite. Tri (mixed mono-and dinonylphenyl) phosphite is particularly suitable.
Suitable triazoles include benzotriazole and alkyl-substituted benzotriazoles having 1 or 2 alkyl groups containing 1 to 10 carbon atoms, preferably 1 carbon atom. Benzotriazole is available under the trade name Cobratec 99 from Sherwin-Williams Chemical. A partic-ularly suitable alkyl-substituted triazole iq tolyltriazole which is available under the trade name Cobratec TT-100 from Sherwin-Williams Chemical.

7~'7'7 Suitable partial esters of an alkyl or alkenyl-succinic anhydride are the products obtained by the reaction of one molar equivalent of a polyhydric alcohol with two molar equivalents of the anhydride. Structurally, these materials are represented by the formula C(O)OH f (o) OH
R-f-H H-f-R
. R'-f-H H-C~R"
C-(O)OR"- O(O)C n wherein of the radicals R and R' one is hydrogen and the other is an alkyl or alkenyl group containing from 8 to 15 carbon atoms and R" is the residue of the polyhydric alcohol which generically may contain oxygen, sulfur, or - nitrogen in the chain as well as ester substituents, and preferably contains from 3 to 6 carbon atoms. The integer n represents a number from 1 to 4. In so doing, n include , in the residue, derivatives of diols, triols, and other polyhydroxy compounds.
A preferred partial ester for use in our invention ,~ 20 is represented by the formula ~- O O
, 11 11 f-OH f-OH
R-C-H H-C-R
,.,,. l l R'-f-H H-F-R' 25ICl OR"O-C

wherein of R and R', one represents hydrogen and the other , a branched chain dodecenyl group and R" iS an alkylene group of 3 to 6 carbon atoms.

A commercially available partial ester which can ~1474~7`7 - be used in our invention is "Hitec" E536*, available from Edwin Cooper Company, St. Louis, Missouri.
The preparation of and additional information concerning these partial esters are provided by U.S. Patent No. 3,117,901.
Tricresyl phosphate is a well known chemical, being represented by the formula (C6H4Me)P04. Any high quality, commercially available tricresyl phosphate can be used.
Diphenylamine or alkylated diphenylamines containing 10 1 or 2 alkyl groups containing about 4 to about 16 carbon atoms per group can be used in the compositions of our invention. The latter-named material is preferred. A suitable commercially available alkylated diphenylamine is "~augalube" 438-L*, available from the Chemical Division of UNIROYAL. This material is predominantly P,P'-dinonyldiphenylamine. It has the following physical properties: Specific Gravity -- 0.99; Flash Point ; -- 350-F: Viscosity, 100-F, SUS -- 3900; Viscosity -- 210-F
-- 86 SUS.
Phenyl a-naphthylamine and phenyl ~-naphthylamine are suitable for use in our invention. Preferred materials of this type are phenyl a-naphthylamine, or phenyl ~-naphthylamine, having 1 or 2 alkyl or alkaryl substituents, each of which contains 1 to about 16, preferably about 6 to about 8, carbon atoms. A suitable commercially available material of the latter type is ~Naugalube~ 460-C*, available from the Chemical Division of UNIROYAL. This material is a mixture of a major amount of di-styrenated phenylbetanaphthylamine and a minor amount of mono-styrenated phenylbetanaphthylamine. It * Trade M æks ~V~ 77 has the following typical properties: Specific Gravity --1.05; Percent Ash -- C0.1; Percent Nitrogen -- 2.8-2.9.
The vinyl-pyrrolidone--a-olefin copolymers which are suitable for use in our invention are characterized as being the reaction product of N-vinyl-2-pyrrolidone and 0.5 to 12 moles of an a-olefin containing 8 to 30 carbon atoms, preferably 18 to 22 carbon atoms. The materials have a , molecular weight of about 2,000 to about 20,000, preferably 7,000 to 12,000. Details on the preparation and properties of the copolymers are provided in U.S. Patent Nos. 3,296,134 and 3,423,3~1. The preferred copolymer is the reaction product of 1 mole of N-vinyl-2-pyrrolidone and 1 mole of a C-20 a-olefin. An example of a commercially available preferred copolymer is "Ganex" V-220*, which is available from GAF
Corporation, 140 West 51st Street, New York, New York. This material has the following physical properties:
, i';
Physical Form, 25-C waxy solid '~ Relative Viscosity (1) 1.007 Density (2) o.gs 20 Average Molecular Weight (3) 8,600 - Softening Point 30C

Melting Range (4) 32-36-C

(1) 0.1 g/100 ml toluene used as solvent ' (2) gm/cc @ 23C

(3) Molecular weight number average determined by High Speed Osmometer in toluene at 25C

*Trade Mark , . , - ~047~77

(4) Determined on the Mannheim Block ; Amounts of Materials Used The amounts of the various materials used in the turbine oil compositions of our invention are shown below, in both suitable and preferred ranges.
Amount (Weight Percent) Material Suitable ~Prefe~-ed Phosphite 0.05-1.5 0.10~1.0 Diphenylamine (or alkylated diphenylamine) 0.02-0.75 0.05-0.50 Phenyl-naphthylamine0.10-0.75 0.15-0.35 Triazole 0.002-0.10 0.005-0.030 Partial Ester of Alkyl or Alkenyl Succinic Anhydride 0.02-0.50 0.05-0.10 Copolymer of N-vinyl-2-pyrrolidone and -olefin0.05-1.500.10-0.80 As is implied, the balance of the composition is -the base lubricating oil, it being understood that other ; 20 conventional lubricant additives can be included, if desired.
Use of Other Materials in Our Invention In describing our invention, we have shown only the essential materials which are used therein. It is to be understood that other conventional lubricating oil additives can be used in the composition, if desired.
Examples of other such materials include, but are not limited to, antifoam agents, pour point depreRsants, viscosity and viscosity index improvers, and dyes.
In order to disclose the nature of the present invention still more clearly, the following examples, both illustrative and comparative, will be given. It is to be ~047477 understood that the invention is not to be limited to the specific conditions or details set forth in these examples except insofar as such limitations are specified in the appended claims.
Test Methods ,,, The test methods used to evaluate the various compositions, both illustrative and comparative, were the following:
~- (1) Federal Test Method 5308.6 of Standard 791 b.
(2) Rotary Bomb Oxidation Test ASTM-D-2272 , (3) ASTM-D-943 Oxidation Test (4) Heat Stability Test Inasmuch as the first of these tests are standard, published tests, it is not believed necessary that they be described herein.
Since the data from the Federal Test Method 5308.6 was used more consistently, this test will be :--~ described in some detail. Usually in this test, the only - values obtained are oil viscosity change, acid number change, and the weight loss of the metal test specimens.
In addition to these values, we obtained the amount of solids deposited or formed during the test. This value is expressed as milligrams of solids per 100 grams of oil sample. In our opinion, this value is a good indicator of the tendency to cause residues in operation of a turbine, which, in turn, can impair performance.
A description of Federal Test Method 5308.6 follows:
A 100-ml test sample, on which viscosity in centistokes at 100F and neutralization number have been --11-- !

:. --1047~'77 measured, is subjected to a temperature of 347F for a period of 72 hours in the presence of 5 liters of air per hour and polished, cleaned, weighed copper, silver, steel, . . .
magnesium, and aluminum coupons held rigidly in a specific arrangement.
The test apparatus consists of a test tube (to contain the test sample) which is fitted with vertical water-cooled condenser and air-delivery tube extending to within 1/8" of the bottom of the test tube. The tube is ~ 10 submerged its entire length except for the joint and ?. . condenser in a constant temperature bath at test tem-:
perature.
, At the end of the test period specified, these observations and measurements are made and recorded:
- 15 (a) Condenser deposits (liquid or solid) appearance.
(b) Viscosity change, % viscosity change from original at 100F, centistokes and neutralization number change from original are determined on filtered oil.
(c) Deposits or solids contained in oil sample, in test cell, and on coupons are collected on a filter paper and their weight determined to the nearest 0.1 mg.
(d) Metal coupons are washed and weighed to establish loss or gain to the nearest 0.1 mg.
(e) Deposits adhering to test cell after scraping and ; 25 washing are rated for appearance in vapor, oil-air interface, and bottom of test cell.
A heat stability test was used to measure Cu-Pb bearing corrosion. Briefly, this test can be described as follows:
A copper-lead faced steel coupon, 1 x 3", is , 'i' t- ~ ";~,"~

.
iO47477 cleaned in accordance with the established procedure and weighed. Two hundred milliliters of test sample is placed ` in a 400-ml tall form beaker. The test coupon is placed in the beaker, which is then covered with a watch glass, and placed in a 250F oven for 96 hours. At the end of the specified period of time the beaker is removed and allowed to cool. The coupon is removed, washed with hexane, dried, and weighed.
- In the following examples the materials used were as follows. Base oils "X" and "Y" were mineral lubricating oils. Also, both base oils were pale oils. Base oil "X"
had a viscosity of lO0 SSU at 100F, while ba~e oil "Y"
had a viscosity of 170 SSU at 100F.
- The materials, other than base oils, used in the compositions tested were as follows:
Triazole "Cobratec" - 50-I
Phosphite Triphenyl Phosphite Partial Ester "Hitec" - E-536 Antifoam Agent Commercially availabl,e silicone Alkylated diphenyl amine "Naugalube" 438-L
Phenyl-~-naphthylamine "Naugalube" 460-C
Copolymer "Ganex" - V-220 ~
The amounts of the various materials used in the compositions tested, stated in weight percent, were as follows:

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- lV4~77 The results of the tests on Compositions A-E are . shown in Table I following while the test results on Compositions F-I are shown in Table II. For purposes of comparison, the results of tests on a commercial high temperature oil (understood as suitable for use in gas ,. turbines) and a typical steam turbine oil are provided in Table III.
... .

. ~ .
:` .
' 1047~ ~ 7 :, ~, O ~ o~ . ~r o ~ . . ~ .~ ~ ~ o U~ Ot~l-l + + + + + I +

. ~"
, r~ N ~ ~ N O ~ ~ ~ ~ O
N IJ ) ~ a~ O U~
. . ~ ~ ~ . . N N ~ ~
O IJ ) ~ O N N + + + + + +
:
,' Z
H ~ O ~1 O O O ~ 1~ Il' 11 O ~ N O ~ l + + + + + N

:
~ ~r N o~ ~ 0 N co ~ ~ ~ 0 0 n 'm~ m l U~ O ~ O +O O+ + O O ~j N
., ~ .' ,.,~
a~ D N ~ _I ~ N ~ ~0 ~

'7 + :' ' R~ ~ ~ n V . .,~ ' o ~ tl) ~ ~ V

1047~77 ~., .
. . _, ~ or~ r~1 ~ r~ ~ U~ r--l O )-I h N U~ 0 `",: ~ ,,~, o . ,,~ ~ ,~ .. . . ~ F: N
.. H ~ D r--l o ,~ ~ + + ~--I o ,.' ,., ,.~' ~ ~D ~ ~ r~ O r5~ r~ O ~D r,~ U~ r~ r~ O r~
-. O + r+ O+ ~ +O ~ ~ , ',': Z
H
" ~ H
.''' ~ ,, :,` r~ H
o u~ O ~ ~ + + +o o+ +

~.^

., .,. H
' ~
U~ ~ ~ r~ OOD~ o~ r, o ... ~ er . O O O ,1 0 1 I
I U~ O U~ ~-1 o ~ 1 + + + + _ , ~
., .

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c~ zO zO 0~ m s _I tn u ~ o H i~ ~ 1 3 0 ~o47~77 ,_~ . O O u'l r~ N 11 ,a ~ ~ ox 1` .. .... .
I In _l O ~1 0 0 _~ Co ~¢ O
~ ~ I +
o .,1 ~
U:~

~ O O~1 U~ O ~ O ~ t` ~ er U
.,1 ~ O11') ~) ~ . . - . O
~10 ~ o. . ~ o ~I t~
o ~I~ +++++
o +
Q~1 E~~ o + .

'. .
', ',' .
': H I

.
O '' a~ ~u U
. E~ ,1 o U ~ U
3 ~ z 0 O I ~g o o ~ .
O I ~ 3 v, o~ooJ~ ~u e :~ ~ù
,, ,~ e ~ ~ O
s~ ~q a) ~ ~ u ~ rl O
a) ,~D O O O Sl o ~1 ~ z ~ ~ e ,~ ~ u ra ~ xo ~ U~ ~ O ~ Q. a) ~ ~
~ O ~~ O ~ rl O ~ 0 _1 0 ~ 0 ,C ~ o U~ U U~
u ~ o ~ z u a ~ o- o 3 E~ ~u~ ~2 7~'7 ., . A comparison of the test results on Compositions ; A-H with the test results on the commercial oils shows that the latter are inferior to Compositions A-H. Of Composi-tions A-H, Composition G is considered to have the best overall properties. A comparison of the test results on ,- Composition I, which contains additionally the copolymer, with Composition G shows that Composition I provides better : corrosion results, better viscosity results, and better neutralization number results. It follows that Composition , 10 I gives better test results than the commercial oils. The , data supports this statement.
, Thus, having described the invention in detail, it will be understood by those skilled in the art that ., certain variations and modifications may be made without departing from the spirit and scope of the invention as defined herein and in the appended claims.
We claim:

~ .

.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A turbine oil composition comprising a major amount of a mineral or synthetic hydrocarbon base lubricating oil and the following combination of materials in the amount specified as weight percent of total composition:
(a) about 0.05 to about 1.5 -triphenyl phosphite or trialkyl-substituted phenyl phosphite having 1 or 2 alkyl substituents, each of which contains 1 to 12 carbon atoms;
(b) about 0.02 to about 0.75 diphenylamine or alkylated diphenylamines containing 1 or 2 alkyl groups, on one or both phenyl moieties, containing from about 4 to about 16 carbon atoms:
(c) about 0.10 to about 0.75 phenyl .alpha.-naphthylamine, phenyl .beta.-naphthylamine, phenyl .alpha.-naphthylamine having 1 or 2 alkyl or alkaryl substituents, each of which contains 1 to about 16 carbon atoms, and phenyl .beta.-naphthylamine having 1 or 2 alkyl or alkaryl substituents, each of which contains 1 to about 16 carbon atoms:
(d) about 0.002 to about 0.10 -benzotriazole or alkyl-substituted benzotriazoles having 1 or 2 alkyl groups containing 1 to 10 carbon atoms: and (e) about 0.02 to about 0.50 -partial ester of an alkyl or alkenyl succinic anhydride, which is represented by the formula wherein of the radicals R and R', one is hydrogen and the other is an alkyl or alkenyl group containing from 8 to 15 carbon atoms, R" is a residue of a polydric alcohol containing from 3 to 6 carbon atoms, and n is an integer of at least one but less than five.

2. The turbine oil composition of Claim 1 wherein the base lubricating oil is a mineral oil.

3. The turbine oil composition of Claim 2 wherein it contains about 0.05 to about 1.50 weight percent of a copolymer of 1 mole N-vinyl-2-pyrrolidone and 0.5 to 12 moles of an .alpha.-olefin containing 8 to 30 carbon atoms.

4. The turbine oil composition of Claim 3 wherein it contains a copolymer of about 1 mole of N-vinyl-2-pyrrolidone and about l mole of a C20 .alpha.-olefin.

5. The turbine oil composition of Claim 1 wherein the base lubricating oil is a synthetic hydrocarbon lubricant which is selected from the group consisting of di-n-long-chain alkaryls, linear mono-olefin oligomers, and a composition consisting essentially of di-n-long-chain alkaryls and trialkyl-substituted tetrahydronaph-thalenes, wherein (a) the term di-n-long-chain alkaryls refers to materials represented by the formula wherein R and R1 are substantially straight-chain alkyl groups containing from 6 to 18 carbon atoms, with the sum of R and R1 being from about 20 to about 28 and wherein A and A
are hydrogen or a C1 or C2 alkyl group, (b) the term linear mono-olefin oligomer refers to materials prepared from .alpha.-olefins containing 6 to 16 carbon atoms and which contain at least 50 weight percent of materials containing 24 to 60 carbon atoms, and (c) the term trialkyl-substituted tetrahydronaphtha-lenes refers to materials represented by the formula wherein R1 and R2 are straight-chain alkyl groups containing from 1 to about 13 carbon atoms each, with the sum of R1 and R2 being from about 6 to about 14, and wherein R3 and R4 are straight-chain alkyl groups containing from about 1 to about 16 carbon atoms, with the sum of R3 and R4 being from about 9 to about 17.

6. The turbine oil composition of Claim 5 wherein it contains about 0.05 to about 1.50 weight percent of a copolymer of 1 mole of N-vinyl-2-pyrrolidone and 0.5 to 12 moles of an .alpha.-olefin containing 8 to 30 carbon atoms.

7. The turbine oil composition of Claim 6 wherein it contains a copolymer of about 1 mole of N-vinyl-2-pyrrolidone and about 1 mole of a C20 .alpha.-olefin.

8. A turbine oil composition comprising a major amount of a mineral or synthetic hydrocarbon base lubricating oil and the following combination of materials in the amounts specified as weight percent of total composition:
(a) about 0.10 to about 1.0 - triphenyl phosphite or tri (mixed mono- and dinonylphenyl) phosphite;
(b) about 0.05 to about 0.50 - diphenylamine or alkylated diphenylamine which is predominantly p,p'-dinonyldiphenylamine;
(c) about 0.15 to about 0.35 - phenyl .alpha.-naphthylamine, phenyl .beta.-naphthylamine or a substituted phenyl .beta.-naphthylamine which is a mixture of a major amount of di-styrenated phenyl .beta.-naphthylamine and a minor amount of mono-styrenated phenyl .beta.-naphthylamine;
(d) about 0.005 to about 0.030 benzotriazole or tolyltriazole;
(e) about 0.05 to about 0.10 partial ester of an alkyl or alkenyl succinic anhydride, which is represented by the formula wherein of the radicals R and R', one is hydrogen and the other is an alkyl or alkenyl group containing from 8 to 15 carbon atoms, R" is a residue of a polydric alcohol containing from 3 to 6 carbon atoms, and n is an integer of at least one but less than five.

9. The turbine oil composition of Claim 8 wherein the base lubricating oil is a mineral oil.

10. The turbine oil composition of Claim 9 wherein it contains about 0.10 to about 0.80 weight percent of a copolymer of 1 mole N-vinyl-2-pyrrolidone and 0.5 to 12 moles of an .alpha.-olefin containing 8 to 30 carbon atoms.

11. The turbine oil composition of Claim 10 wherein it contains a copolymer of about 1 mole of N-vinyl-2-pyrrolidone and about 1 mole of a C20 .alpha.-olefin.

12. The turbine oil composition of Claim 8 wherein the base lubricating oil is a synthetic hydrocarbon lubricant which is selected from the group consisting of di-n-long-chain alkaryls, linear mono-olefin oligomers, and a composition consisting essentially of di-n-long-chain alkaryls and trialkyl-substituted tetrahydronaph-thalenes, wherein (a) the term di-n-long-chain alkaryls refers to materials represented by the formula wherein R and R1 are substantially straight-chain alkyl groups containing from 6 to 18 carbon atoms, with the sum of R and R1 being from about 20 to about 28 and wherein A and A1 are hydrogen or a C1 or C2 alkyl group, (b) the term linear mono-olefin oligomer refers to materials prepared from .alpha.-olefins containing 6 to 16 carbon atoms and which contain at least 50 weight percent of materials containing 24 to 60 carbon atoms, and (c) the term trialkyl-substituted tetrahydronaph-thalenes refers to materials represented by the formula wherein R1 and R2 are straight-chain alkyl groups containing from 1 to about 13 carbon atoms each, with the sum of R1 and R2 being from about 6 to about 14, and wherein R3 and R4 are straight-chain alkyl groups containing from about 1 to about 16 carbon atoms, with the sum of R3 and R4 being from about 9 to about 17.

13. The turbine oil composition of Claim 12 wherein the partial ester of succinic anhydride is repre-sented by the formula wherein of R and R' one represents hydrogen and the other a branched chain dodecenyl group and R" is an alkylene group of 3 to 6 carbon atoms.

14. The turbine oil composition of Claim 13 wherein it contains about 0.10 to about 0.80 weight percent of a copolymer of 1 mole N-vinyl-2-pyrrolidone and 0.5 to 12 moles of an .alpha.-olefin containing 8 to 30 carbon atoms.

15. The turbine oil composition of Claim 14 wherein it contains a copolymer of about 1 mole of N-vinyl-2-pyrrolidone and about 1 mole of a C20 olefin.

16. The turbine oil composition of Claim 15 wherein the base lubricating oil is a composition con-sisting essentially of di-n-long-chain alkaryls, which are present in an amount of 61 to 92 weight percent, and trialkyl-substituted tetrahydronaphthalenes which are present in an amount of 5 to 30 weight percent.