Patent ID: 8722595

Claim:
A lubricating oil composition comprising a hydrogenated refined mineral base oil that has a % C A value of 10 or less as measured by ring analysis, a sulfur content of 300 ppm by mass or less and a viscosity index of 70 or more; 0.1 to 3% by mass based on the total composition of a dialkylphenylamine antioxidant selected from the group consisting of 4,4′-dibutyldiphenylamine, 4,4′-dipentyldiphenylamine, 4,4′-dihexyldiphenylamine, 4,4′-diheptyldiphenylamine, 4,4′-dioctyldiphenylamine, and 4,4′-dinonyldiphenylamine; and 0.5 to 2% by mass based on the total composition of a phosphorus compound having a structure represented by the following formula (I): wherein R 1 , R 2 , and R 4 are each independently an alkyl group having 1 to 8 carbon atoms R 3 is a hydrogen atom or a methyl group; R 5 is an alkyl group having 1 to 5 carbon atoms; X is a simple bond, A is an alkylene group having 2 to 8 carbon atoms, and one of Y and Z is a hydroxyl group and the other of Y and Z is a hydrogen, wherein the composition has a phosphorus content of 0.12% by mass or less and a sulfated ash content of 1.2% by mass or less on the basis of an amount of the composition.