| abstract |
A lubricating oil composition comprising at least one base oil selected from among mineral-oil-based lubricating oils, synthetic-oil-based lubricating oils, and mixed oils each comprising two or more of these and zinc dialkyldithiophosphates X comprising Z 1 to Z 3 represented by formulae (1) to (3), wherein the X is contained in a total amount in terms of phosphorus concentration of 0.02 mass% or larger with respect to the mass of the whole composition and satisfies relationships (a) to (c). In formula (1), R 1 to R 4 each independently represent a linear or branched C 10-20 primary alkyl group. In formula (2), R 5 to R 8 each independently represent a linear or branched C 7-9 primary alkyl group. In formula (3), R 9 to R 12 each independently represent a linear or branched, C 3-6 primary or secondary alkyl group. Relationships (a) to (c) are shown in the description. |