Abstract: The present invention provides a lubricating oil composition comprising a mixture of both a poly-alpha-olefin and an ester compound, the lubricating oil composition having an SAE viscosity grade of 75W-85, satisfying GL-5 in terms of API gear oil designation and having a viscosity index of 160 or more. The above mixture of the poly-alpha-olefin and ester compound is preferably contained in an amount of from 75 to 90 wt % with reference to the total amount of the lubricating oil composition. The poly-alpha-olefin is preferably a mixture of a poly-alpha-olefin having low viscosity of from about 3 to 6 mm2/s at 100° C. and a poly-alpha-olefin having high viscosity of from about 35 to 45 mm2/s at 100° C.

Abstract: The present invention provides a gear oil composition for vehicle driving systems, more specifically a gear oil composition for vehicle final reduction gears, which can improve a fuel-saving effect by reducing its viscosity and, at the same time, secure bearing fatigue life characteristics. The gear oil composition comprises a base oil (A) and another base oil (B), described below, and at least one species of additive for gear oil, and has a kinematic viscosity of 80 mm2/s or less at 40° C.: (A): a mineral-based oil and/or hydrocarbon-based synthetic oil having a kinematic viscosity of 3.5 to 7 mm2/s at 100° C., and (B): a mineral-based oil and/or hydrocarbon-based synthetic oil having a kinematic viscosity of 20 to 52 mm2/s at 100° C.

Abstract: The present invention provides a lubricating oil composition comprising a mixture of both a poly-alpha-olefin and an ester compound, the lubricating oil composition having an SAE viscosity grade of 75 W-85, satisfying GL-5 in terms of API gear oil designation and having a viscosity index of 160 or more. The above mixture of the poly-alpha-olefin and ester compound is preferably contained in an amount of from 75 to 90 wt % with reference to the total amount of the lubricating oil composition. The poly-alpha-olefin is preferably a mixture of a poly-alpha-olefin having low viscosity of from about 3 to 6 mm2/s at 100° C. and a poly-alpha-olefin having high viscosity of from about 35 to 45 mm2/s at 100° C.

Abstract: The present invention provides a gear oil composition for vehicle driving systems, more specifically a gear oil composition for vehicle final reduction gears, which can improve a fuel-saving effect by reducing its viscosity and, at the same time, secure bearing fatigue life characteristics. The gear oil composition comprises a base oil (A) and another base oil (B), described below, and at least one species of additive for gear oil, and has a kinematic viscosity of 80 mm2/s or less at 40° C.: (A): a mineral-based oil and/or hydrocarbon-based synthetic oil having a kinematic viscosity of 3.5 to 7 mm2/s at 100° C., and (B): a mineral-based oil and/or hydrocarbon-based synthetic oil having a kinematic viscosity of 20 to 52 mm2/s at 100° C.

Abstract: In a parallel-axis differential, a pair of sun gears are received in a housing in a coaxial relation. Also, at least a pair of planetary gears are received in the housing in parallel relation with the sun gears. The planetary gears of the pair are in engagement with the pair of sun gears, respectively and also in engagement with each other. A window opening for introducing lubricating oil is formed in the housing. Also, a fin for guiding the lubricating oil toward the window opening is formed on the outer surface of the housing. The fin is situated on the rear side of the window opening with reference to one rotating direction of said housing.