Lubricating oil composition and method for using lubricating oil composition

A lubricating oil composition comprising:

• a base oil (X) comprising tertiary carbon atom at a content of 8.0 at % or more based on the total carbon of hydrocarbons;
• and
• an antioxidant (Y) comprising an amine-based antioxidant (A), a phenol-based antioxidant (B), and a phosphor-based antioxidant (C),
• wherein the amine-based antioxidant (A) comprises a diphenylamine compound (A1) represented by the following general formula (a1):
• wherein Ra1 and Ra2 are each independently an alkyl group having 1 to 30 carbon atoms, na1 and na2 are each independently an integer of 1 to 5, wherein when na1 is 2 or more, a plurality of Rai's may be the same, or may be different from each other, and in the case where na2 is 2 or more, a plurality of Ra2's may be the same, or may be different from each other,
• the phenol-based antioxidant (B) comprises a hindered phenol compound (B1) having an ester structure, and
• the total content [(A1)+(B1)+(C)] of the diphenylamine compound (A1), the hindered phenol compound (B1) having an ester structure, and the phosphor-based antioxidant (C) based on the total amount of the lubricating oil composition is greater than 1.0 mass % and 2.0 mass % or less.