Patent ID: 8609596

Claim:
A gear oil composition comprising a mineral base oil, (A) an ashless dithiocarbamate compound, and (B) an ester of pentaerythritol and isostearic acid, wherein said ashless dithiocarbamate compound is present in the gear oil composition in an amount of from 1 to 5.0% by mass based on the total amount of the gear oil composition, said ester having a hydroxyl value of 20 to 100 mg KOH/g and present in an amount of from 0.1 to 8.0% by mass based on the total amount of the gear oil composition, and said ashless dithiocarbamate compound comprises at least one compound represented by formula (1) where R 1 to R 4 may be the same or different and each represents a C 1 to C 30 hydrocarbon group and R 5 represents a C 1 to C 10 alkylene group.