| abstract |
A lubricating oil composition for an internal combustion engine, which comprises a base oil for a lubricating oil comprising a mineral oil and/or a synthetic oil, (A) 0.001 to 0.5 mass % of an ester of boric acid in terms of boron element and (B) 0.01 to 5 mass % of an ashless antioxidant, both percentages being relative to the total amount of the composition, wherein it contains substantially no metal salt of dithiophosphoric acid and has a sulfur content of 0.2 mass % or less. The lubricating oil composition is extremely excellent in the retention of the base number, the detergency at a high temperature, and the prevention of the cam lifter wear, and also contains substantially no phosphorus and/or sulfur containing anti-wear additive. |