Lubricant composition

A lubricating oil composition, comprising:

• a lubricant base oil;
• a phosphate ester derivative represented by formula (1) below:
• wherein:
• Y represents S (sulfur) or O (oxygen);
• R1 represents an organic group having 4 to 24 carbon atoms;
• R2 represents a divalent organic group having 1 to 6 carbon atoms;
• and n represents an integer of 1 to 3;
• a zinc compound, wherein
• an element ratio (Zn/P) between zinc (Zn) and phosphorus (P) in the lubricating oil composition is 0.55-1 at a mole ratio, and
• a metal detergent, a content of the metal detergent being 0.02-0.1941 mass % in terms of metal based on a total amount of the lubricating oil composition,
• wherein
• a sulfated ash content of said composition is 1 mass % or less of the total amount of the composition,
• Y in the phosphate ester derivative of the formula (I) represents O (oxygen),
• a phosphorus content is 0.12 mass % or less of the total amount of the composition,
• the zinc compound is at least one compound selected from the group consisting of metal zinc, a zinc oxide, an organic zinc compound, a zinc oxoacid salt, a zinc halide and a zinc complex,
• the metal detergent is at least one of alkali metal salicylate and alkali earth metal salicylate,
• and wherein the lubricating oil composition further comprises at least one additive selected from the group consisting of an ashless dispersant, a phenol antioxidant, an amine antioxidant, a metal deactivator and an anti-emulsifier.