Lubricating oil composition for internal combustion engines

A lubricating oil composition having a sulfated ash content and being free of molybdenum for internal combustion engines which has a high temperature high shear viscosity according to ASTM D 4683 in the range of from 2.1 to less than 2.9 mPas, which composition comprises lubricating base oil and

• (1) zinc dialkyldithiophosphate having a primary and/or secondary alcohol mixed therewith in a residue so that the phosphorus content in the oil is from 0.04 to 0.12 mass %, wherein the relationship between the primary and secondary alcohol in the zinc dialkyldithiophosphate alcohol residue satisfies the following
• expression in terms of the amount (mass %) of elemental phosphorus in the oil:
• 0.04.ltoreq.(Pri)+(Sec).ltoreq.0.12
• (Pri)=0 to 0.03
• where, (Pri) is the mass % of primary alcohol residue and (Sec) is the mass % of secondary alcohol residue, and
• (2) a metallic detergent selected from the group consisting of calcium alkylsalicylate and ii) a mixture of calcium alkylsalicylate and magnesium alkylsalicylate wherein the lubricating oil sulphated ash content is from 0.8 to 1.8 mass %, according to JIS K2272, and optionally,
• (3) at most 2.0 mass % of friction modifier.