GB2444640A

GB2444640A - Lubricating composition

Info

Publication number: GB2444640A
Application number: GB0723829A
Authority: GB
Inventors: John T Loper; Naresh C Mathur; Paul G Griffin; David A Hutchison
Original assignee: Afton Chemical Corp
Current assignee: Afton Chemical Corp
Priority date: 2006-12-06
Filing date: 2007-12-05
Publication date: 2008-06-11
Anticipated expiration: 2027-12-05
Also published as: JP2008144153A; GB2444640B; GB0723829D0; CN101245277A; US20080139421A1; DE102007049975A1; FR2909681B1; FR2909681A1

Abstract

A lubricant composition where oxidative degradation is reduced, comprises a major amount of a base oil and a minor amount of an additive composition comprising <SL> <LI>(i) a triazole compound substituted with an aryl moiety (e.g. a benzotriazole or a tolyltriazole); <LI>(ii) a nitrogen-containing compound represented by the formula R<1>-NH-R<2>, wherein R<1> and R<2> are each selected from at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and <LI>(iii) a phenolic compound. </SL>

Description

LUBRICATING COMPOSITION

DESCRIPTION OF THE DISCLOSURE

Field of the Disclosure

The present disclosure is directed to additive and lubricant compositions and methods for use thereof. More particularly, this invention is directed to an additive composition comprising (i) a tnazole compound, (ii) a nitrogen-containing compound, and (iii) a phenolic compound.

Background ofthe Disclosure

Lubricating oils as used in the internal combustion engines and transmissions of automobiles or trucks are subjected to a demanding environment during use. This environment results in oxidation of the oil which is catalyzed by the presence of impurities in the oil, and is also promoted by the elevated temperatures of the oil during use.

The oxidation of lubricating oils contributes to the formation of sludge in oils and the breakdown of viscosity characteristics of the lubricant. The oxidation is often controlled to some extent by selecting the proper antioxidant additives thereby significantly improving the life of the lubricating oils. Antioxidant additives can extend the useful life of the lubricating oil by, for example, reducing or preventing unacceptable viscosity increases and/or deposit formation.

Additionally, protecting the metal surface of an engine against wear degradation by selecting the proper balance of antiwear agents in a lubricating composition can significantly increase the life of the metal surface. Antiwear agents form a thin-film on metal surfaces which prevents metal to metal contact, resulting in a decrease in the amount of wear. A well-known and commonly used antiwear agent is zinc dialkyldithiophosphate (ZDDP).

However, the demanding environment in which lubricating oils are subjected, including high temperatures and/or high pressures, decompose ZDDP in a lubricating oil composition. Studies have shown that some exhaust emission catalysts can be deactivated by phosphorus, largely derived from ZDDP compounds which have been the mainstay antiwear agents in passenger car motor oil and heavy duty diesel formulations for the past 50 years. Consequently, future engine oils will likely contain reduced phosphorus levels. Furthermore, as ZDDP decomposes and releases zinc molecules, these zinc molecules are capable of reacting with other performance additives present in the lubricating composition, creating sludge and other particulate matter that can cause adverse effects on engine performance. These undesirable effects of oxidation present problems in meeting ever more severe engine performance requirements.

Simply lowering the amount of ZDDP is not a practical solution to the problem because of the accompanying reduction of antiwear properties. Therefore, it would be desirable for a lubricating oil composition to comprise improved additives that reduce the oxidative degradation of lubricating oils. It has now been discovered that a composition comprising (i) a triazole compound substituted with an aryl moiety, (ii) a nitrogen-containing compound, and (iii) a phenolic compound can provide a highly effective system which can inhibit oxidation.

SUMMARY OF THE DISCLOSURE

In accordance with the disclosure, there is provided an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I): R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

In an aspect, there is also provided a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising (I) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I): R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

Moreover, there is provided a method of decreasing oxidation degradation of a lubricant composition, said method comprising providing to a machine a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising (i) a triazole-compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I): R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

Further, there is provided a method for operating a machine, said method comprising adding to the machine a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising (I) a triazole compound substituted with an aryf moiety; (ii) a nitrogen-containing compound represented by the formula (I): R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

Furthermore, there is provided a method of lubricating at least one moving part of a machine, said method comprising contacting the at least one moving part with a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I): R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

Also provided is the use of the additive composition of the invention to delay the onset of viscosity increase in a lubricant.

Additional objects and advantages of the disclosure will be set forth in part in the description which follows, and/or can be learned by practice of the disclosure. The objects and advantages of the disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not

restrictive of the disclosure, as claimed.

DESCRIPTION OF THE EMBODIMENTS

The present disclosure generally relates to a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising (I) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by formula (I):

H

N

R1 R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

As used herein, the term "major amount" is understood to mean an amount greater than or equal to 50 wt. %, for example from about 80 to about 98 wt.% relative to the total weight of the composition. Moreover, as used herein, the term "minor amount" is understood to mean an amount less than 50 wt. % relative to the total weight of the composition.

As used herein, "aromatic' or "aryl", unless expressly stated otherwise, refers to the typical substituted or unsubstituted non-atiphatic hydrocarbyl or heterocyclic moieties of this class, e.g., a polyunsaturated, typically aromatic, hydrocarbyl cyclical, or heterocyclic, substituent, which can have a single ring or multiple rings (up to three rings) that are fused together or linked covalently.

Typical hydrocarbyl aromatic moieties include phenyl, naphthyl, biphenylenyl, phenanthrenyl, phenalenyt, and the like. Such moieties are optionally substituted with one or more substituted or unsubstituted hydrocarbyl substituents. In one embodiment, the substituents on the substituted hydrocarbyl substituents are themselves unsubstituted. Typically, the hydrocarbyl substituents are unsubstituted. Aryl moieties can also be optionally substituted with one or more substituents such as hydroxy, optionally substituted lower alkyl, optionally substituted lower alkoxy, amino, amide, ester moieties and carbonyl moieties (e.g., aldehyde or ketonic moieties). Also included are aryl moieties substituted by other aryl moieties, such as biphenyl. Heterocyclic aryl or aromatic moieties refers to unsaturated cyclical moieties containing carbon atoms in the ring and additionally one or more hetero atoms, which are typically oxygen, nitrogen, sulfur and/or phosphorus, such as pyridyl, thienyl, furyl, thiazolyl, pyranyl, pyrrolyl, pyrazolyl, imidazolyl, pyrazinyl, thiazolyt, etc. Such moieties are optionally substituted with one or more substituents such as hydroxy, optionally substituted lower alkyl, optionally substituted lower alkoxy, amino, amide, ester moieties and carbonyl moieties (e.g., aldehyde or ketonic moieties). In one embodiment, an aryl moiety comprises from 3 to 30, for example from 6 to 30, carbon atoms.

As used herein, "alkaryl", unless expressly stated otherwise, refers to an alkyl moiety substituted by the typical substituted or unsubstituted non-

F

aliphatic hydrocarbyl or heterocyclic moieties described above. Typical aryl moieties include phenyl, naphthyl, benzyl, and the like. Such moieties are optionally substituted with one or more substituents such as hydroxy, optionally substituted alky, optionally substituted alkoxy, amino, amide, ester moieties and carbonyl moieties (e.g., aldehyde or ketonic moieties).

As used herein, the terms "hydrocarbon", "hydrocarbyl" or ahydrocarbon based" mean that the moiety being described has predominantly hydrocarbon character within the context of this invention. These include moieties that are purely hydrocarbon in nature, that is, they contain only carbon and hydrogen. They can also include moieties containing substituents or atoms which do not alter the predominantly hydrocarbon character of the moiety. Such substituents can include halo, alkoxy, nitro, etc. These moieties also can contain hetero atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, sulfur, nitrogen, oxygen, and phosphorus. Therefore, while remaining predominantly hydrocarbon in character within the context of this invention, these moieties can contain atoms other than carbon present in a chain or ring otherwise composed of carbon atoms.

In one embodiment, an alkyl group is a linear or branched alkyl group containing from I to 32 carbon atoms, for example from I to 24 carbon atoms. A lower alkyl group typically refers to a said alkyl group which contains from I to 12 carbon atoms, for example from I to 6 carbon atoms. An alkyl group can be substituted by one or more substituents, for example one, two or three substituents, which are the same or different and are selected from halogen, hydroxy, alkoxy, In one embodiment, a cycloalkyl group is cyclic form of a said alkyl group which comprises from 3 to 32 carbon atoms, preferably from 3 to 12, for example 5 or 6, carbon atoms. A cycloalkyl group can comprise one or more ring systems.

In one embodiment, an alkoxy group is a group -OR, wherein R is an alkyl group as defined above. An optionally substituted lower alkoxy group is a group -OR wherein R is an alkyl group which contains from I to 12 carbon atoms, for example I to 6 carbon atoms, and is unsubstituted or substituted by one or more substituents, for example one, two or three substituents, which are the same or different and are selected from halogen, hydroxy, alkoxy, amino and thio In one embodiment, a halogen is typically fluorine, chlorine, bromine or iodine and is preferably fluorine, chlorine or bromine, such as fluorine or chlorine.

In one embodiment, an amino group is a group -NRR' wherein R and R' are the same or different and represent hydrogen or an alkyl group containing from I to 32 carbon atoms, for example from I to 24 carbon atoms.

In one embodiment, a thio group is a group -SR wherein R represents hydrogen or an alkyl group containing from I to 32 carbon atoms, for example from I to 24 carbon atoms.

In one embodiment, a sulfono group is a group -SO2R wherein R represents hydrogen or an alkyl group containing from I to 32 carbon atoms, for example from I to 24 carbon atoms.

In one embodiment, an amido group is a group -C(O)NRR' wherein R and R' are the same or different and represent hydrogen or an alkyl group containing from I to 32 carbon atoms, for example from 1 to 24 carbon atoms.

In one embodiment, a phosphoro group is a group -P(O)RR' wherein R and R' are the same or different and represent hydrogen or an alkyl group containing from 1 to 32 carbon atoms, for example from I to 24 carbon atoms.

In one embodiment, an ester group is a group -C(O)OR wherein R represents hydrogen or an alkyl group containing from I to 32 carbon atoms, for example from 1 to 24 carbon atoms.

In one embodiment; a carbonyl group is a group -C(O)R wherein R represents hydrogen or an alkyl group containing from 1 to 32 carbon atoms, for example from 1 to 24 carbon atoms.

In one embodiment, an alkenyl group is a linear or branched alkylene group containing from I to 32 carbon atoms, for example from I to 24 carbon atoms. Typically, an alkenyl group or moiety is saturated except for one double bond. An alkenyl group can be substituted by one or more substituents, for one, two or three substituents, which are the same or different and are selected from halogen, hydroxy, alkoxy, amino and thio substituents.

In one embodiment, a cycloalkenyt group is cyclic form of a said alkenyl group which comprises from 3 to 32 carbon atoms, preferably from 3 to 12, for example 5 or 6, carbon atoms. A cycloalkenyl group can comprise one or more ring systems.

In one embodiment, a cyclic moiety is typically a non-aromatic saturated or unsaturated hydrocarbon ring, having from 3 to 12 carbon atoms. A cyclic moiety can also be a non-aromatic, saturated or unsaturated hydrocarbon ring having from 3 to 12 carbon atoms in which one or more, for example one, two or three, of the carbon atoms are replaced by a heteroatom selected from N, 0 and S. Typically, the cyclic moiety is unsaturated or has one double bond. The cyclic moiety can comprise one or more ring systems and can also comprise bridging carbon atoms. When the cyclic moiety comprises one or more ring systems, said systems can be linked by covalent bonds or can be fused. In one embodiment, the cyclic moiety comprises two fused rings. A preferred cyclic group is an octahydro- 1 H-indenyl group, for example an octahydro-1-H indenyl group with a methylene bridge between the 4 and 7 positions. A cyclic moiety can be substituted with one or more substituents, for example one, two or three substituents, which are the same or different and are selected from hydroxy, alkoxy, amino, amide, ester, oxo, halogen, nitro, thio, phosphoro or sulfono substituents.

In a preferred embodiment, the term "hydrocarbyl group" or "hydrocarbyl" is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of a molecule and having a predominantly hydrocarbon character.

Examples of hydrocarbyl groups include: (1) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) or aromatic substituents and aromatic-, al iphatic-, and alicycl ic-substituted aromatic substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form an alicyclic radical); (2) substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of the description herein, do not alter the predominantly hydrocarbon substituent (e.g., halo (especially chioro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy); (3) hetero-substituents, that is, substituents which, while having a predominantly hydrocarbon character, in the context of this description, contain other than carbon in a ring or chain otherwise composed of carbon atoms. Hetero-atoms include sulfur, oxygen, nitrogen, and encompass substituents such as pyridyl, furyl, thienyl, and imidazolyf.

In general, no more than two, or as a further example, no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically, there wilt be no non-hydrocarbon substituent in the hydrocarbyl group. In one embodiment, a hydrocarbyl group comprises from I to 32 carbon atoms, for example I to 24 carbon atoms. In one embodiment, a hetero-substituent comprises from I to 32 carbon atoms, for example 1-to 24 carbon atoms, wherein one, two or three of the carbon atoms is replaced by heteroatoms which are the same or different and are selected from sulfur, oxygen and nitrogen.

In one embodiment, the substituents on an alkyl, alkenyl, alkoxy, cyclic and hydrocarbyl moiety are unsubstituted.

A triazole compound suitable for use in the compositions of the present disclosure can be any triazole substituted with an aryl moiety. in some embodiments the triazole compound is an aryl-substitutecj I,2,3-triazole compound.

In other embodiments the triazole compound is an aryl-substituted 1,2,4-triazole compound. In another embodiment, the triazole compound is not an alkyl bis-3-amino-1,2,4-triazole. As used herein, the triazole compound is substituted with an aryl moiety. However, the triazole itself can be further substituted by a substituent such as an alkyl moiety comprising from about 1 to about 24 carbon atoms. Thus, in one embodiment, a triazole substituted with an aryl moiety refers to a triazole ring substituted with an aryl group wherein the triazole ring is further optionally substituted with an alkyl group comprising from about 1 to about 24 carbon atoms.

The aryl moiety can be linked to the triazole via a covalent bond, or can be fused to the triazole.

As an example, the triazole compound can be substituted with a substituted or unsubstituted aryl moiety comprising a single ring or multiple rings, for example covalently linked rings. Non-limiting examples of substituted aromatic moieties comprising covalently linked rings include biphenyl, 1,1'-binaphthyl, p,p'-bitolyl, biphenylenyl, and the like. As another example, the aryl moiety can comprise multiple fused rings. Non-limiting examples of aryl moieties comprising multiple fused rings include naphthyl, anthryl, pyrenyt, phenanthrenyl, phenalenyl, and the like. As a further example, the aryl moiety can comprise a single ring covalently linked to the tnazole. Non-limiting examples of aryl moieties comprising a single ring covalently linked to the triazole include phenyl and the like. As another example, the aryl moiety can comprise a single ring fused to the tnazole.

Non-limiting examples of aryl moieties comprising a single ring fused to the triazole include benzotriazole and tolyltriazole. An example of a commercially available triazole compound suitable for use herein is a benzotriazole, which is an off-white solid having a melting point ranging from 95-99 C, a flashpoint of 170 C, and a water solubility of 25 gIL at 20 C. The triazole compound can be combined/reacted/mixed with other additives in order to increase its solubility in a composition.

In an embodiment, the triazole compound can be represented by formula (II) below: (II) wherein R3 is selected from the group consisting of hydrogen and an alkyl moiety comprising from about I to about 24 carbon atoms, and wherein R4 is selected from the group consisting of hydrogen, an alkyl moiety comprising from about 1 to about 24 carbon atoms, and a substituted hydrocarbyl moiety. In another embodiment, R3 and R4 of the triazole compound represented by formula (II) can each independently comprise from about I to about 16 carbon atoms. In one embodiment, when R4 is an alkyl moiety it is an unsubstituted alkyl moiety.

The triazole compound can be present in the disclosed lubricant and additive compositions in any effective amount, which can be readily determined by one of ordinary skill in the art. In an embodiment, the lubricating composition of the present disclosure can comprise from about 0.05 wt.% to about 0.5 wt.%, and for example from about 0.1 wL% to about 0.3 wt.% of the triazole compound, relative to the total weight of the lubricating composition. In another embodiment, the additive composition of the present disclosure can comprise from about 0.48 wt.% to about 5 wt.% of the tnazole compound, relative to the total weight of the additive composition.

The disclosed composition can also comprise a nitrogen-containing compound for various uses. There is no particular restriction on the type of nitrogen-containing compound that can be used in the disclosed composition of the present disclosure. Generally, a nitrogen-containing compound suitable for use herein can be represented by formula (I) below: R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono. For example, R1 and R2 can each independently comprise an aryl moiety comprising from about 6 to about 30 carbon atoms. Non-limiting examples of aryl moieties which can comprise R1 and R2 include phenyl benzyl, naphthyl, and alkaryl. As another example, R1 and R2 can each independently comprise alkaryl, such as alkphenyl or alknaphthyl, wherein the alkyl moiety comprises from about 4 to about 30 carbon atoms, and for example from about 4 to about 12 carbon atoms.

As still another example, R1 and R2 can each independently comprise a substituted or unsubstituted aryl moiety. Non-limiting examples of substituents for the aryl moiety can include an atkyl moiety comprising from about 1 to about 20 carbon atoms, hydroxyl, carboxyl, and nitro moieties. As another example, R1 and R2 can each independently be an alkyl substituted benzyl, phenyl, or naphthyl.

Other non-limiting examples of nitrogen-containing compounds that are suitable include: phenylamine; diphenylamine; triphenylamine; various alkylated phenylamines, diphenylamines and triphenylamines; N,N'-bis(4-aminophenyl)..

alkylamine; 3-hydroxydiphenylamine; N-phenyl-1,2-phenylenedian,ine; N-phenyl- 1,4-phenylenediamirie; dibutyldiphenylamine; dioctyldiphenylamine; dinonyldiphenylamine; phenyl-alpha-naphthylamine; phenyl-beta-naphtylamine; diheptyldiphenylamine; and p-oriented styrenated diphenylamine. Additional non-limiting examples of suitable nitrogen-containing compounds and their methods of preparation include those in U.S. Patent No. 6,218,576, which descriptions are incorporated herein by reference.

The nitrogen-containing compounds used herein can comprise a structure other than that shown above in formula (I) which shows but one nitrogen atom in the molecule. Thus, the nitrogen-containing compound can comprise a

V

different structure provided that at least one nitrogen has at least one ar-yl moietyattached thereto, e.g., as in the case of various diamines having a secondary nitrogen atom as welt as an aryl attached to one of the nitrogens.

The nitrogen-containing compounds used herein can have antioxidant properties in the disclosed compositions when used atone or in combination as described herein. The nitrogen-containing compounds used herein should be soluble in a final lubricant composition.

The amount of the nitrogen-containing compound inthe lubricating compositions can vary depending upon specific requirements and applications. In an embodiment, the lubricating composition of the present disclosure can comprise from about 0.2 wt.% to about 1.2 wt.%, and for example from about 0.4 wt.% to about 1.0 wt.%, of the nitrogen-containing compound, relative to the total weight of the lubricating composition. In another embodiment, the additive compositions of the present disclosure can comprise from about 2 wt.% to about 12 wt.% of the nitrogencontaining compound, relative to the total weight of the additive composition.

A phenolic compound suitable for use in compositions of the present disclosure can be any phenol, provided that it is soluble in a lubricant composition.

For example, the phenolic compound can be substituted at one or both ortho positions. Examples of such phenolic compounds include 2-tert-butylphenol, 2- ethyl-6-methyl phenol, 2,6-di-tert-butyl-phenol, 2,6-di-tert-butyl-4-methylphenol, 2,2'-methylene-bis-4,6di-tert-butyl-phenoj, 4,4'-methylene-bis (2,6-di-tert-butyl-phenol), 2,2'-propylidene-bis (6-tert-butyl-4-methylphenol), and mixtures thereof. As another example, the phenolic compound can be an esterified reaction product of a phenol and an unsaturated carboxytic acid comprising at least one double bond. In an embodiment, the phenolic compound can be represented by formula (III) below: R6 (Ill) wherein R5 and R6 are each independently selected from the group consisting of hydrogen, an alkyl moiety comprising from about 1 to about 24 carbon atoms, and a cyclic moiety comprising from about 3 to about 12 carbon atoms, and R7 is selected from the group consisting of hydrogen, alkyt, aryl, alkaryl, and (CH2)COOR8, wherein n is an integer from I to 4, inclusive and R8 is an alkyl moiety comprising from about I to about 18 carbon atoms. The cyclic moiety can include polycychc ring systems, such as bicyclic and tricyclic groups. In another embodiment, the phenolic compound can be an oligomer. In yet another embodiment, the phenolic compound can be an estenfied reaction product of 2,6-di-tert-butyl phenol and acrylic acid. An example of a commercially available phenolic compound suitable for use herein is 3,5-di-tert-butyl-4-hydroxyphenol propionate, which is a clear, yellow to amber liquid having a viscosity of 120 mm2/s at 40 C and a density of 0. 96 g/cm3 at 20 C. Another example of a commercially available phenolic compound suitable for use herein is a high molecular weight oligomer of a butylated reaction product of p-cresol and dicyclopentadiene, which is a light powder or yellowish flakes having a melting point of 105 C. One example of such an oligomer is represented by formula (IV) below: (IV) wherein n is any integer greater than 10, such as, for example, an integer greater than about 100, or in other examples, an integer greater than about 1000.

The phenolic compound can be present in the disclosed lubricant and additive compositions in any effective amount, which can be readily determined by one of ordinary skill in the art. In an embodiment, the lubricating composition of the present disclosure can comprise from about 0.05 wt.% to about 1.2 wt.%, and for example from about 0.1 wt.% to about 0.8 wt.% of the phenolic compound, relative to the total weight of the lubricating composition. In another embodiment, the additive composition of the present disclosure can comprise from about 0.5 wt.% to about 12 wt.% of the phenolic compound, relative to the total weight of the additive composition.

The compositions disclosed herein can optionally contain additives, such as phosphorus-containing compounds, dispersants, ash-containing detergents, ashless-detergents, overbased detergents, pour point depressing agents, viscosity index modifiers, ash-containing frictionmodifiers, ashless friction modifiers, nitrogen-containing friction modifiers, nitrogen-free friction modifiers, esterified friction modifiers, extreme pressure agents, rust inhibitors, antioxidants, corrosion inhibitors, anti-foam agents, titanium compounds, titanium complexes, organic soluble molybdenum compounds, organic soluble molybdenum comptexes, boron-containing compounds, boron-containing complexes, and combinations thereof. In an aspect, the phosphorus-containing compounds, for example zinc dialkyldithiophosphate salts, in the lubricant composition may be present in an amount sufficient to provide from about 100 to about 1000 parts per million by weight of total phosphorus in the lubricant composition. In another aspect, the phosphorus-containing compounds may be present in an amount sufficient to provide from about 600 to about 800 parts per million by weight of total phosphorus in the lubricant composition. In yet another aspect, the compositions can comprise various levels of at least one titanium-containing compound depending. on the needs and requirements of the application.

Base oils suitable for use in formulating the disclosed compositions can be selected from any of the synthetic or mineral oils or mixtures thereof.

Mineral oils include animal oils and vegetable oils (e.g., castor oil, lard oil) as well as other mineral lubricating oils such as liquid petroleum oils and solvent treated or acid-treated mineral lubricating oils of the paraffinic, naphthenic or mixed paraffinic-naphthenic types. Oils derived from coal or shale are also suitable. Further, oils derived from a gas-to-liquid process are also suitable.

The base oil can be present in a major amount, wherein "major amount" is understood to mean greater than or equal to 50%, for example from about 80 to about 98 percent by weight of the lubricant composition.

The base oil typically has a viscosity of, for example, from about 2 to about 150 cSt and, as a further example, from about 5 to about 15 cSt at 100 C.

Thus, the base oils can normally have a viscosity in the range of about SAE 15 to about SAE 250, and more usually can range from about SAE 20W to about SAE 50. Suitable automotive oils also include cross-grades such as 1 5W-40, 20W-50, 75W-140, 80W-90, 55W-140, 85W-90, and the like.

Non-limiting examples of synthetic oils include hydrocarbon oils such as polymenzed and interpolymerized olefins (e.g., polybutylenes, polypropylenes, propylene isobutylene copolymers, etc.); polyal phaolefins such as poly(1-hexenes), poly-(1-octenes), poly(1-decenes), etc. and mixtures thereof; alkylbenzenes (e.g., dodecylbenzenes, tetradecyl benzenes, di-nonylbenzenes, di- (2-ethylhexyl)benzenes, etc.); polyphenyls (e.g., biphenyls, terphenyl, alkylated polyphenyls, etc.); alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs and homologs thereof and the like.

Alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl moieties have been modified by esterification, etherification, etc., constitute another class of known synthetic oils that can be used. Such oils are exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methyl-polyisopropylene glycol ether having an average molecular weight of about 1000, diphenyl ether of polyethylene glycol having a molecular weight of about 500-1000, diethyl ether of polypropylene glycol having a molecular weight of about 1000-1 500, etc.) or mono-and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C fatty acid esters, or the C,3 Oxo acid diester of tetraethylene glycol.

Another class of synthetic oils that can be used includes the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids, alkenyl succinic acids, maleic acid, azelaic acid, subenc acid, sebacic acid, fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, alkenyl malonic acids, etc.) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, propylene glycol, etc.) Specific examples of these esters include dibutyl adipate, di(2-ethyl hexyl)sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyi azelate, dilsodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethyihexanoic acid and the like.

Esters useful as synthetic oils also include those made from C5i2 monocarboxylic acids and polyols andpolyol ethers such as neopentyl giycol, tn methylol propane, pentaerythritol, dipentaerythritol, tnpentaerythritol, etc. Hence, the base oil used which can be used to make the compositions as described herein can be selected from any of the base oils in Groups I-V as specified in the American Petroleum Institute (API) Base Oil Interchangeability Guidelines. Such base oil groups are as follows: Group I contain less than 90% saturates and/or greater than 0. 03% sulfur and have a viscosity index greater than or equal to 80 and less than 120; Group II contain greater than or equal to 90% saturates and less than or equal to 0.03% sulfur and have a viscosity index greater than or equal to 80 and less than 120; Group III contain greater than or equal to 90% saturates and less than or equal to 0.03% sulfur and have a viscosity index greater than or equal to 120; Group IV are polyalphaolefins (PAO); and Group V include all other basestocks not included in Group I, II, Ill or IV.

The test methods used in defining the above groups are ASTM D2007 for saturates; ASTM D2270 for viscosity index; and one of ASTM D2622, 4294, 4927 and 3120 for sulfur.

Group IV basestocks, i.e. polyalphaolefins (PAO) include hydrogenated oligomers of an aipha-olefin, the most important methods of oligomerisation being free radical processes, Ziegler catalysis, and cationic, Friedel-Crafts catalysis.

The polyalphaolefins typically have viscosities in the range of 2 to cSt at 100 C.. for example 4 to 8 cSt at 100 C. They can, for example, be oligomers of branched or straight chain aipha-olefins having from about 2 to about carbon atoms, non-limiting examples include polypropenes, polyisobutenes, poly-1-butenes, poly-1-hexenes, poly-1-octenes and poly-1-decene. Included are homopolymers, interpolymers and mixtures.

Regarding the balance of the basestock referred to above, a "Group I basestock" also includes a Group I basestock with which basestock(s) from one or more other groups can be admixed, provided that the resulting admixture has characteristics falling within those specified above for Group I basestocks.

Exemplary basestocks include Group I basestocks and mixtures of Group II basestocks with Group I bright stock.

Basestocks suitable for use herein can be made using a variety of different processes including but not limited to distillation, solvent refining, hydrogen processing, oligomerisation, esterification, and re-refining.

The base oil can be an oil derived from Fischer-Tropsch synthesized hydrocarbons. Fischer-Tropsch synthesized hydrocarbons can be made from synthesis gas containing H2 and CO using a Fischer-Tropsch catalyst.

Such hydrocarbons typically require further processing in order to be useful as the base oil. For example, the hydrocarbons can be hydroisomerized using processes disclosed in U.S. Pat. No. 6,103,099 or 6,180,575; hydrocracked and hydroisomerized using processes disclosed in U.S. Pat. No. 4,943,672 or 6,096,940; dewaxed using processes disclosed in U.S. Pat. No. 5,882,505; or hydroisomerized and dewaxed using processes disclosed in U.S. Pat. No. 6,013,171; 6,080,301; or 6,165,949.

Unrefined, refined and rerefined oils, either mineral or synthetic (as well as mixtures of two or more of any of these) of the type disclosed hereinabove can be used in the base oils. Unrefined oils are those obtained directly from a mineral or synthetic source without further purification treatment. For example, a shale oil obtained directly from retorting operations, a petroleum oil obtained directly from primary distillation or ester oil obtained directly from an esterification process and used without further treatment would be an unrefined oil. Refined oils are similar to the unrefined oils except they have been further treated in one or more purification steps to improve one or more properties. Many such purification techniques are known to those skilled in the art such as solvent extraction, secondary distillation, acid or base extraction, filtration, percolation, etc. Rerefined oils are obtained by processes similar to those used to obtain refined oils applied to refined oils which have been already used in service. Such rerefined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques directed to removal of spent additives, contaminants, and oil breakdown products.

According to various embodiments, there is disclosed a method of delaying the onset of viscosity increase in a lubricant composition. As used herein, the term "delaying the onset of viscosity increase" is understood to mean delaying the start of an increase in the viscosity of a lubricant composition due to the oxidation process, as compared to a composition that is devoid of the compositions of the present application, including a triazole compound substituted with an aryl moiety, a nitrogen-containing compound, and a phenolic compound, as disclosed herein. The method of delaying the onset of viscosity increase in a lubricant composition can comprise providing to a machine a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive comprising (I) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by formula (I): R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

According to various embodiments, there is also disclosed a method of lubricating at least one moving part of a machine. As used herein, "at least one moving part of a machine" is understood to mean at least one part of a machine which is capable of being in motion, including a gear, piston, bearing, rod, spring, camshaft, crankshaft, and the like. The method of lubricating at least one moving part of a machine comprises contacting the at least one moving part with a lubricant composition comprising a major amount of a base oil; and a minor amount of the disclosed additive composition.

In other embodiments, there is also disclosed a method for operating a machine comprising adding to the machine a lubricant composition comprising a major amount of a base oil and a minor amount of the disclosed additive composition.

The machine in the disclosed methods can be selected from the group consisting of spark ignition and compression-ignition internal combustion engines. Moreover, the at least one moving part can be chosen from a gear, piston, bearing, rod, spring, camshaft, crankshaft, and the like.

The lubricant composition can be any composition that would be effective in lubricating a machine. In an aspect, the composition is selected from the group consisting of passenger car motor oils, medium speed diesel engine oils, and heavy duty diesel engine oils.

EXAMPLES

The following examples are illustrative of the invention and its advantageous properties. In this example, as well as elsewhere in this application, all parts and percentages are by weight unless otherwise indicated.

Compositions according to the present application were formulated comprising atriazole compound substituted with an aryl moiety, a nitrogen-containing compound, a phenolic compound, and a base composition, as shown in Tables I and 2. The triazole compound employed in Example Compositions I and 2 was a commercially available tolyltriazole (Cobratec TT-100, PMC Specialties Group, Cincinnati, Ohio). The nitrogen-containing compound was an alkylated diphenylamine (Hi-TEC 7190, Afton Chemical Corporation, Richmond, VA), and the phenolic compound was a commercially available transesterified phenol (Ethanox 4716, Albemarle Corporation, Richmond, VA). A comparative example was formulated without a triazole compound, as shown in Table 3 using the same nitrogen-containing compound, phenolic compound, and base composition as in Example Compositions I and 2.

TABLE I -Example Composition 1 with Antioxidant System COMPONENT Wt.% Triazole 0.2 Aryl amine 0.8 Phenolic antioxidant #1 0.1 ZDDP 0.08 TEOST MHT-4 Base Composition Remainder (mg) 36.5 TABLE 2-Example Composition 2 with Antioxidant System COMPONENT Wt.% Triazole 0.2 Aryiamine 0.4 PhenoHc antioxidant #2 0.2 ZDDP 0.08 TEOST MHT-4 Base Composition Remainder (mg) 31.1 TABLE 3-Comparative Example Composition 3 COMPONENT Wt.% Triazole --Ar1 amine 0.8 Phenolic antioxidant #1 0.1 ZDDP 0.05 TEOST MHT-4 15 Base Composition Remainder (mg) 48 The base composition for Example Compositions 1-3 included ingredients within the concentration ranges shown for Base 2 of Table 4 below.

The base composition was formulated with a base stock meeting the GF-5 standards set forth by the International Lubricants Standardization and Approval Committee (ILSAC), which in the instant example, was a SAE grade 5W-30 type motor oil. All values are stated as weight percent.

I

TABLE 4

Example Base Compositions Base I Base 2 (Wt.%) (Wt.%) Dispersant system 0.15-15 1-10 Metal Detergents 0.1-15 0.2-8 Corrosion Inhibitor 0-5 0-2 Metal Dihyd rocarbyl Dithiophosphate 0.1-6 0.1-4 Antifoaming Agent 0- 5 0.001-0.15 Friction Modifier 0-5 0-2 Supplemental Antiwear Agents 0-1.0 0-0.8 Pour Point Depressant 0.01-5 0.01-1.5 Viscosity Modifier o:oi-io 0.25-7 Base stock Balance Balance A thermo-oxidation engine oil simulation test (TEOST MHT-4) was performed on Example Compositions 1 and 2 and Comparative Example Composition 3. The TEOST M1-IT-4 is a standard lubricant industry test for the evaluation of the oxidation and carbonaceous deposit-forming characteristics of lubricants. The test is designed to simulate high temperature deposit formation in the piston ring belt area of modern engines. The test utilizes a patented instrument (U.S. Pat. No. 5,401,661 and U.S. Pat. No. 5,287,731)with the MHT-4 protocol being a relatively new modification to the test. The lower amount of deposit indicates better oxidation control thereby delaying the onset of viscosity increase in a lubricant composition.

The results demonstrated the advantage of using the disclosed composition to delay the onset of viscosity increase in a lubricant composition. As shown by the foregoing example, Example Composition 1 comprising the disclosed antioxidant system demonstrated a TEOST MI-IT-4 score of 36.5 mg. Similarly, Example Composition 2 comprising the disclosed antioxidant system demonstrated a TEOST MHT-4 score of 31.1 mg. In comparison, Example Composition 3 which did not comprise the disclosed composition demonstrated a much higher TEOST MHT-4 score of 48 mg. Thus, it can be seen that the disclosed composition surprisingly and significantly reduces piston deposits thereby delaying the onset of viscosity increase in a lubricant composition.

It is intended that the examples are being presented for the purpose of illustration only and are not intended to limit the scope of the invention disclosed herein. As would be understood by one of ordinary skill in the art, the particular ingredients employed and the concentrations of the ingredients can differ from those used in the examples. For instance, prophetic examples are contemplated which employ ingredients in concentrations outside of the ranges of Base 2, such as within the ranges set forth for Base I of Table 4, above.

It is noted that, as used in this specification and the appended claims, the singular forms "a," "an," and "the," include plural referents unless expressly and unequivocally limited to one referent. Thus, for example, reference to "an antioxidant" includes two or more different antioxidarits. As used herein, the term "include" and its grammatical variants are intended to be non-limiting, such that recitation of items in a list is not to the exclusion of other like items that can be substituted or added to the listed items.

For the purposes of this specification and appended claims, unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term "about" Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the present disclosure. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

While particular embodiments have been described, alternatives, modifications, variations, improvements, and substantial equivalents that are or can be presently unforeseen can arise to applicants or others skilled in the art.

Accordingly, the appended claims as flied and as they can be amended are intended to embrace all such alternatives, modifications variations, improvements, and substantial equivalents.

Claims

1. An additive composition comprising: (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I): R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one ary moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

2. The additive composition of claim 1, wherein the triazole compound is substituted with a substituted aryl moiety comprising multiple rings.

3. The additive composition of claim 1, wherein the triazole compound is substitutedwith a substituted aryl moiety comprising a single ring.

4. The additive composition of claim 1, wherein the triazole compound is represented by the formula (II):

N N NR4 (II)

wherein R3 is selected from the group consisting of hydrogen and an alkyl moiety comprising from about I to about 24 carbon atoms, and wherein R4 is selected from the group consisting of hydrogen, an alkyl moiety comprising from about I to about 24 carbon atoms, and a substituted hydrocarbyl moiety.

5. The additive composition of any one of the preceding claims, wherein the triazole compound is not an alkyl bis-3-amino-1,2,4-tnazole.

6. The additive composition of any one of the preceding claims, wherein the phenolic compound comprises an esterified reaction product of 2,6-di-tert-butyl phenol and an unsaturated carboxylic acid comprising at least one double bond and from about 3 to about 24 carbon atoms.

7. The additive composition of any one of the preceding claims, wherein the phenolic compound is represented by the formula (Ill): R6 R7 (Ill) wherein R5 and R6 are each independently selected from the group consisting of hydrogen, an alkyl moiety comprising from about I to about 24 carbon atoms, and a cyclic moiety comprising from about 3 to about 12 carbon atoms, and R7 is selected from the group consisting of hydrogen, alkyl, aryl, alkaryl, and (CH2)COOR8, wherein n is an integer from I to 4, inclusive and R8 is an alkyl moiety comprising from about I to about 18 carbon atoms.

8. The additive composition of any one of the preceding claims, wherein the phenolic compound is 3,5-di-tert-butyl-4-hydroxy phenol propionate.

9. The additive composition of claim 7 wherein the phenolic compound is a compound of formula (Ill) or an oligomer thereof.

10. The additive composition of any one of the preceding claims, wherein the triazole compound is present in an amount ranging from about 0.48 wt.% to about 5wt.%.

11. The additive composition of any one of the preceding claims, wherein the nitrogen-containing compound is present in an amount ranging from about 2 wt.% to about 12 wt.%.

12. The additive composition of any one of the preceding claims, wherein the phenolic compound is present in an amount ranging from about 0.5 wt.% to about 12 wt.%.

13. The additive composition of any one of the preceding claims, further comprising at least one additive selected from the group consisting of phosphorus-containing compounds, dispersants, ashcontaining detergents, ashless-detergents, overbased detergents, pour point depressing agents, viscosity index improving agents, ash-containing friction modifier, ashless friction modifier, nitrogen-containing friction modifier, nitrogen-free friction modifier, esterified friction modifier, extreme pressure agents, rust inhibitors, supplemental antioxidants, corrosion inhibitors, anti-foam agents, titanium compounds, titanium complexes, organic soluble molybdenum compounds, organic soluble molybdenum complexes, boron-containing compounds, and boron-containing complexes.

14. A lubricant composition comprising: a major amount of a base oil; and a minor amount of an additive composition comprising (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I): R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfonti and (iii) a phenolic compound.

15. The lubricant composition of claim 14, wherein the triazole compound is present in an amount ranging from about 0.05 wt.% to about 0. 5 wt.%.

16. The lubricant composition of either claim 14 or claim 15, wherein the tnazole compound is present in an amount ranging from about 0.1 wt.% to about 0.3 wt.%.

17. The lubricant composition of any one of claims 14 to 16, wherein the nitrogen-containing compound is present in an amount ranging from about 0.2 wt.% to about 1.2 wt.%.

18. The lubricant composition of any one of claim 14 to 17, wherein the nitrogen-containing compound is present in an amount ranging from about 0.4 wt.% to about 1.0 wt.%.

19. The lubricant composition of any one of claims 14 to 18, wherein the phenolic compound is present in an amount ranging from about 0.05 wt% to about 1.2 wt.%.

20. The lubricant composition of any one of claims 14 to 19, wherein the phenolic compound is present in an amount ranging from about 0.1 wt.% to about 12 wt.%.

21. The lubricant composition of any one of claims 14 to 20, wherein the additive composition is as defined in any one of claims I to 12.

22. The lubricant composition of any one of claims 14 to 21, further comprising at least one additive selected from the group consisting of phosphorus- containing compounds, dispersants, ash-containing detergents, ashless-detergents, overbased detergents, pour point depressing agents, viscosity index improving agents, ash-containing friction modifier, ashless friction modifier, nitrogen-containing friction modifier, nitrogen-free friction modifier, esterified friction modifier, extreme pressure agents, rust inhibitors, supplemental antioxidants, corrosion inhibitors, anti-foam agents, titanium compounds, titanium complexes, organic soluble molybdenum compounds, organic soluble molybdenum complexes, boron-containing compounds, and boron-containing complexes.

23. The lubricant composition of any one of claims 14 to 22, further comprising at least one titanium-containing compound.

24. The lubricant composition of any one of claims 14 to 23, further comprising a phosphorus-containing compound in an amount ranging from about 100 to about 1000 ppm of total phosphorus in a lubricant composition.

25. The lubricant composition of any one of claims 14 to 24, wherein the phosphorus-containing compound is in a concentration ranging from about 600 to about 800 ppm of total phosphorus in the lubricant composition.

26. The lubricant composition of any one of claims 14 to 25, wherein the lubricant composition is selected from the group consisting of passenger car motor oil, medium speed diesel engine oil, and heavy duty diesel engine oil.

27. A method of delaying the onset of viscosity increase in a lubricant composition, said method comprising: providing to a machine a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition-comprising: (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I): R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

28. A method of lubricating at least one moving part of a machine, said method comprising: contacting the at least one moving part with a lubricant composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising: (I) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I): R1R2 (I)

S

wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

29. A method of operating a machine comprising: adding to the machine a lubricating composition comprising a major amount of a base oil; and a minor amount of an additive composition comprising: (i) a triazole compound substituted with an aryl moiety; (ii) a nitrogen-containing compound represented by the formula (I): R1R2 (I) wherein R1 and R2 are each independently selected from the group consisting of at least one aryl moiety comprising from about 6 to about 30 atoms, hydrogen, halogen, hydroxy, hydrocarbyl, substituted hydrocarbyl, amino, amido, phosphoro, and sulfono; and (iii) a phenolic compound.

30. The method of any one of claims 27 to 29, wherein the machine is selected from the group consisting of spark ignition and compression-ignition internal combustion engines.

31. The method of any one of claims 27 to 29 wherein the lubricant composition is as defined in any one of claims 14 to 26.

32. Use of an additive composition according to any one of claims 1 to 13 to delay the onset of viscosity increase in a lubricant.

33. An additive composition according to claim 1 and substantially as herein before described.

34. A lubricating composition according to claim 14 and substantially as hereinbefore described.

35. A method according to claim 27, claim 28 or claim 29 and substantially as hereinbefore described.

36. Use according to claim 32 and substantially as hereinbefore described.