Lubricating oil composition

A lubricating oil composition comprising a lubricating base oil and on the basis of the total mass of the composition, (A) a boron-containing ashless dispersant in an amount of 100 to 500 ppm by mass as boron, (B) a phosphorus additive in an amount of 300 to 800 ppm by mass as phosphorus, (C) an amide- and/or imide-based friction modifier in an amount of 1 to 4 percent by mass, and (D) an alkali metal- and/or alkaline earth metal-based detergent in an amount of 100 to 300 ppm by mass as metal, wherein the composition has a 40° C. kinematic viscosity of 25 mm2/s or lower and a 100° C. kinematic viscosity of 6.5 mm2/s or lower,

• wherein Component (B) comprises a combination of a phosphite ester and phosphoric acid having a ratio ([P2]/[P1]) of the phosphorus amount [P2] of the phosphoric acid to the phosphorus amount [P1] of the phosphite ester of 0.2 to 1.0;
• wherein Component (D) comprises a metallic detergent having a base number of less than 150 mgKOH/g and has a ratio ([M]/[P]) of the metal amount [M] of the metallic detergent to the phosphorus amount [P] of Component (B) of 0.06 to 0.25;
• wherein the phosphite ester is a phosphite ester having an (alkyl)aryl group having 6 to 12 carbon atoms and the metallic detergent is a calcium sulfonate detergent.