Lubricating oil composition

A lubricating oil composition comprising:

• (O) a lubricant base oil comprising at least one mineral base oil or at least one synthetic base oil or any combination thereof, and having a kinematic viscosity at 40° C. of 6.0 to 12.0 mm2/s;
• (A) a condensation reaction product of a polyisobutenylsuccinic acid or anhydride thereof and a first polyamine, or a modified product thereof, or any combination thereof, in an amount of no less than 80 mass ppm in terms of nitrogen and no more than 2.7 mass % as an entire compound on the basis of the total mass of the composition, the polyisobutenylsuccinic acid having a polyisobutenyl group, the polyisobutenyl group having a number average molecular weight of no less than 800;
• (B) a condensation reaction product of an alkyl- or alkenyl-succinic acid having a C8-30 alkyl or alkenyl group or anhydride thereof and a second polyamine, or a modified product thereof, or any combination thereof, in an amount of 50 to 1300 mass ppm in terms of nitrogen on the basis of the total mass of the composition,
• wherein a product of a weight average molecular weight (unit:
• Da) of the component (A) and the amount of the component (A) as the entire compound (unit:
• mass %) is no more than 16,000.