Patent ID: 9102897
Filing Date: 2015-08-11
Classification: C10M,C10N

Abstract:
1. A lubricating oil composition for transmissions which comprises a lubricating base oil consisting essentially of (A) from 60 to 95 percent by mass, based on the total amount of the base oil, of a hydrocracked mineral oil and/or a wax-isomerized isoparaffin base oil so adjusted to have a kinematic viscosity at 100° C. of from 1.5 to 4 mm 2 /s, a viscosity index of 110 or more, and a % C N of from 10 to 26.2 and (B) from 5 to 40 percent by mass, based on the total amount of the base oil, of a mineral lubricating base oil having a kinematic viscosity at 100° C. of from 16 to 50 mm 2 /s, a % C N of from 15 to 40, and a sulfur content of from 0.3 to 1 percent by mass, and (D) from 0.05 to 2 percent by mass, based on the total amount of the composition, of an extreme pressure additive consisting essentially of a phosphorus-based extreme pressure additive selected from the group consisting of phosphoric acid, phosphorous acid, and phosphorous acid esters and a sulfur-based extreme pressure additive selected from the group consisting of sulfurized fats and oils, dihydrocarbyl polysulfides represented by formula (2) below, thiadiazoles, and benzothiazoles, wherein R 13 and R 14 are each independently a saturated alkyl group or a cycloalkyl group having 1 to 20 carbon atoms, and y is an integer of 2 to 8; wherein in the composition, the phosphorus content (P) is from 0.01 to 0.05 percent by mass, the total sulfur content (S) is from 0.05 to 0.3 percent by mass, and the P/S ratio of the phosphorus content contained in Component (D) to the total sulfur content in the composition is from 0.21 to 0.40, the composition has a kinematic viscosity at 100° C. of 3 to 6.5 mm