Lubricating oil composition

A lubricating oil composition, comprising:

• a base oil;
• a zinc dithiophosphate;
• and
• a sarcosine compound,
• wherein a content of the sarcosine compound is 0.10% by mass or more and 0.40% by mass or less based on the entire amount of the lubricating oil composition, a content of the base oil is 65% by mass to 95% by mass based on the entire amount of the lubricating oil composition, a content of the zinc dithiophosphate is 1.00% by mass to 1.40% by mass based on the entire amount of the lubricating oil composition, the base oil has a 100° C. kinematic viscosity of 1 mm2/s or more and 25 mm2/s or less, the lubricating oil composition satisfies a requirement (α) or (β) where the requirement (α) requires that when the content of the sarcosine compound is 0.10% by mass or more and less than 0.20% by mass based on the entire amount of the lubricating oil composition, one or more phosphorus compounds selected from the group consisting of an acidic phosphoric acid ester and an amine salt thereof are optionally contained, and a content of the one or more phosphorus compounds is 1.25% by mass or less based on the entire amount of the lubricating oil composition, and the requirement (β) requires that when the content of the sarcosine compound is 0.20% by mass or more and 0.40% by mass or less based on the entire amount of the lubricating oil composition, the one or more phosphorus compounds is contained in an amount less than 0.50% by mass based on the entire amount of the lubricating oil composition, the lubricating oil composition has a coefficient of friction μ50 of 0.114 or less at a rotation speed of 50 rpm, a test oil temperature of 80° C. and a surface pressure of 1 MPa, measured on a friction plate and a steel plate by a low velocity slipping friction apparatus tester based on JASO M 349, the lubricating oil composition has a load withstanding capacity of more than 0.50 MPa, measured with a Soda four-ball tester at a rotation speed of 200 rpm according to JIS K2519, the base oil is a mineral oil, the zinc dithiophosphate has formula (b-1),
• where Rb1, Rb2, Rb3 and Rb4 each independently are an alkyl group having 1 to 24 carbon atoms, the sarcosine compound conforms to has formula (c-2),
• where RC3 is a hydrocarbon group having 1 to 29 carbon atoms, the acidic phosphoric acid ester has formula (d-1),
• where Rd1's each independently are an alkyl group having 2 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms, and m is 1 or 2, and the amine salt is formed from the acidic phosphoric acid ester and an amine of formula (d-2),
• R
• n
• d
• ⁢
• 2
• -
• NH
• 3
• -
• n
• (
• d
• -
• 2
• )
• where Rd2 is an alkyl group having 6 to 18 carbon atoms, and n is 1, 2, or 3.