Lubricant Compositions Containing High C9 Disubstituted Diphenylamine Antioxidant Content and Low Mono- and Tri-substituted Diphenylamine Antioxidant Content

A lubricating oil composition comprising from 0.75 to 3 mass % of the lubricating oil composition of diphenyl amine antioxidant comprising:

• 1) 85 to 90 mass % or more of di(C9-alkyl substituted phenyl) amine,
• 2) from 1.5 to 5 mass % of mono-C9-alkyl substituted diphenyl amine,
• 3) from 8 to 11 mass % of tri-C9-alkyl substituted diphenyl amine,
• 4) 0.05 mass % or less of unsubstituted diphenyl amine,
• based upon the total weight of the diphenyl amine antioxidant present in the lubricating oil composition.

Diphenyl amine antioxidant, for use in a lubricating oil composition or a concentrate, comprising:

• a) 1.5 to 13 mass % of mono-C9-alkyl substituted diphenyl amines represented by the Formula (III) where n is 1, z is 0 and w is 0,
• b) 75 to 93 mass % of di-C9-alkyl substituted diphenyl amines represented by Formula (III), where n is 1 and z is 1,
• c) 5 to 12 mass % of tri-C9-alkyl substituted diphenyl amines represented by Formula (III), where n is 1, z is 1 and w is 1,
• d) 0 to 0.10 mass % of unsubstituted diphenyl amine represented by Formula (III) where w is 0, n is 0, and z is 0,
• based upon the total weight of a), b), c) and d) present in the diphenylamine antioxidant, where Formula (III) is:
• where each Ra is independently a linear C9 alkyl or branched C9 alkyl group, n is 1, z is 0 or 1, and w is 0 or 1.

A concentrate composition comprising or resulting from the admixing of:

• (i) 1 to 50 mass % of one or more base oils, based upon the weight of the concentrate composition;
• (ii) one or more dispersants;
• (iii) one or more detergents;
• and
• (iv) diphenyl amine antioxidant comprising:
• 1) 75 to 93 mass % di-C9-alkyl substituted diphenyl amine,
• 2) 1.5 to 13 mass % mono-C9-alkyl substituted diphenyl amine,
• 3) 5 to 12 mass % tri-C9-alkyl substituted diphenyl amine, and
• 4) 0 to 0.10 mass % of unsubstituted diphenyl amine,
• based upon the weight of the mono-C9-alkyl substituted diphenyl amine, tri-C9-alkyl substituted diphenyl amine, substituted diphenyl amine, and di-C9-alkyl substituted diphenyl amine present in the concentrate.