A lubricating oil composition employable in combination with a low sulfur content fuel oil is preferably composed of a base oil having a sulfur content of at most 0.2 wt. %, an ashless dispersant comprising an alkenyl- or alkyl-succinimide or a derivative thereof, a metal-containing detergent containing an organic acid metal salt, a zinc dialkyldithiophosphate, a zinc dialkylaryldithiophosphate, and an oxidation inhibitor selected from the group consisting of a phenol compound, an amine compound, and a molybdenum-containing compound, wherein a ratio of the phosphorus content of the zinc dialkyldithiophosphate to the phosphorus content of the zinc dialkylaryldithiophosphate is in the range of 20:1 to 2:1.