LUBRICATING OIL COMPOSITION FOR INTERNAL COMBUSTION ENGINE

摘要

PROBLEM TO BE SOLVED: To provide a lubricating oil composition for an internal combustion engine having excellent heat/oxidation stability and achieving sufficient long draining. SOLUTION: The lubricating oil composition for the internal combustion engine comprises a lubricating base oil satisfying at least either of conditions (a) or (b), an ashless oxidation inhibitor free of sulfur as a constituent element, at least one kind selected from an ashless oxidation inhibitor containing the sulfur as the constituent element, and an organomolybdenum compound. (a) A lubricating base oil containing≥90 mass% of a saturated component in which the ratio of a cyclic saturated component accounts for 10-40 mass% of the saturated component. (b) A lubricating base oil satisfying conditions represented by formula (1) 1.440≤n20-0.002×kv100≤1.453 (1) [wherein, n20represents the refractive index of the lubricating base oil at 20°C; and kv100 represents the kinematic viscosity (mm2/s) of the lubricating base oil at 100°C]. COPYRIGHT: (C)2007,JPO&INPIT