Cosmo Oil Lubricants Co., Ltd.

Naoki Asami

Koichi Sakamoto

Atsushi Akamatsu

Takuma Saito

A lubricating oil composition includes at least one base oil selected from the group consisting of a mineral oil-based lubricating oil, a synthetic oil-based lubricating oil, and a mixed oil thereof, zinc dialkyldithiophosphate X represented by Formula (1), and an acid phosphate ester amine salt Y represented by Formula (2), in which a content Pof the X is from 0.06% by mass to 0.08% by mass in terms of phosphorus concentration with respect to a total mass of the lubricating oil composition, and a content Pof the Y is from 0.015% by mass to 0.025% by mass in terms of phosphorus concentration with respect to the total mass of the lubricating oil composition.

Lubricating oil composition

A lubricating oil composition including: at least one base oil selected from a mineral oil-based lubricating oil, a synthetic oil-based lubricating oil, or a mixed oil thereof, and zinc dialkyldithiophosphates X consisting of the compounds Zto Zrepresented by the formulae (1) to (3) are contained, in which a total content of the zinc dialkyldithiophosphates X is 0.02% by mass or more in terms of phosphorus concentration with respect to the total mass of the oil composition, and the zinc dialkyldithiophosphates X satisfy the formulae (a) to (c). In the formula (1), each of Rto Rindependently represents a linear or branched primary alkyl group having from 10 to 20 carbon atoms. In the formula (2), each of Rto Rindependently represents a linear or branched primary alkyl group having from 7 to 9 carbon atoms. In the formula (3), each of Rto Rindependently represents a linear or branched primary or secondary alkyl group having from 3 to 6 carbon atoms. The formula (a) to (c) are shown in the specification.

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Saitama, Japan

Naoki Asami