Patent ID: 9540586
Date: 2017-01-10
CPC Classifications: C10M,C10N

Claim:
1. A method of reducing oxidative degradation of a lubricant composition which contains a mineral oil of lubricating viscosity and at least about 1 percent by weight of a C1-C4 alkyl ester of a carboxylic acid of about 12 to about 24 carbon atoms, comprising including within said lubricant composition about 0.8 to about 2 percent by weight of one or more calcium or magnesium sulfonate detergents said calcium or magnesium sulfonate detergents comprising at least one calcium or magnesium sulfonate detergent having a TBN of about 100 to less than 200, in an amount to deliver at least about 0.2 percent by weight sulfonate soap to the lubricant composition and optionally at least one overbased sulfonate detergent having a TBN of 300 to about 750; such that the total amount of sulfonate soap in the lubricant composition from all such sulfonate detergents is an amount sufficient to provide 0.5 to 2 percent by weight sulfonate soap to the lubricant composition, along with a phenate detergent, wherein the weight ratio of sulfonate soap to phenate soap in the lubricant composition is at least about 0.7:1 and up to about 1.5:1, said lubricant composition further comprising a succinimide dispersant.