Abstract: An engine oil composition is composed of: (1) at least one oil selected from the group consisting of a mineral oil and a synthetic lubricant as a base oil; (2) a molybdenum dithiocarbamate in an amount of 50 to 2000 ppm by weight when calculated as molybdenum (Mo), relative to the total weight of the engine oil composition; (3) zinc dithiophosphate in an amount of 0.01 to 0.2 wt % when calculated as phosphorus (P), relative to the total amount of the engine oil composition; and (4) an ashless organic polysulfide compound in an amount of 0.01 to 0.4 wt % when calculated as sulfur (S), relative to the total amount of the engine oil composition.

Abstract: There is disclosed a lubricating oil for internal combustion engine which comprises:a mineral oil and/or a synthetic lubricating oil as a base oil, and oxymolybdenum dithiocarbamate sulfide expressed by the chemical formula (1): ##STR1## wherein R.sub.1 or R.sub.1 and R.sub.3 denote a branched aliphatic hydrocarbon group having not less than fourteen carbons, and R.sub.2 through R.sub.4 or R.sub.2 and R.sub.4 denote an aliphatic hydrocarbon group having not less than four carbons, in the amount of 0.005 to 0.2% by weight, when calculated as molybdenum (Mo).