LUBRICATING OIL COMPOSITION FOR TWO WHEELED VEHICLE, METHOD FOR IMPROVING FUEL ECONOMY OF TWO WHEELED VEHICLE USING THE LUBRICATING OIL COMPOSITION, AND METHOD FOR PRODUCING THE LUBRICATING OIL COMPOSITION

The present invention provides a lubricating oil composition for two-wheeled vehicles, which is able to not only suppress a lowering of fatigue life of engine parts while making fuel saving properties (in particular, fuel saving properties at the time of low speed) favorable but also make clutch friction characteristics of two-wheeled vehicles favorable. The present invention is concerned with a lubricating oil composition for two-wheeled vehicles, including a base oil (A) having a viscosity index of 120 or more, an ethylene-propylene copolymer (B), and a metal-based detergent (C), wherein the content of the ethylene-propylene copolymer (B) is 0.30% by mass or more on the basis of the whole amount of the lubricating oil composition; the metal-based detergent (C) contains a calcium phenate (C1) and a calcium sulfonate (C2), and a mass ratio of the content (Ca1) of the calcium phenate (C1) as expressed in terms of a calcium atom to the content (Ca2) of the calcium sulfonate (C2) as expressed in terms of a calcium atom is satisfied with a relation of (1.0≤Ca1/Ca2); and the lubricating oil composition has a kinematic viscosity at 100° C. is less than 9.3 mm2/s and an HTHS viscosity at 150° C. is 2.9 mPa·s or more.