Gear Oil Compositions, Methods of Making and Using Thereof

Abstract

A gear oil composition is provided. The composition comprises a synergistic blend of mineral oil base stock and polyalphaolefin (PAO) base stock for the oil composition to have a traction coefficient at a slide to roll ratio of 40 percent at 15 mm 2 /s. of 0.030 or less and a pressure viscosity coefficient of at least 16.0 at 80° C., 20 Newton load, and 1.1 m/s rolling speed. In one embodiment, the synergistic amount of PAO base stock ranges from 5 to 48 wt. % based on the total weight of the gear oil composition.

1 . A method for improving the traction properties of a gear oil composition, the method comprises adding a synergistic amount of at least a polyalphaolefin (PAO) base stock to a base oil matrix comprising at least a mineral oil having a kinematic viscosity of 3 to 120 mm 2 /s at 100° C. and a viscosity index of at least 60, for the gear oil composition to have a traction coefficient at a slide to roll ratio of 40 percent at 15 mm 2 /s. of 0.030 or less, a pressure viscosity coefficient of 15.0 or higher at 80° C., 20 Newton load, and 1.1 m/s rolling speed, and a film thickness of greater than 175 nm at 80° C., wherein the PAO base stock has a kinematic viscosity at 40° C. in the range of 80-110 mm 2 /s and a kinematic viscosity at 100° C. of 10-16 mm 2 /s and a viscosity index of 140-160. 
     
     
         2 . The method of  claim 1 , wherein the synergistic amount of at least a polyalphaolefin (PAO) base stock ranges from 5 to 48 wt. % based on the total weight of the gear oil composition. 
     
     
         3 . The method of  claim 2 , wherein the synergistic amount of at least a polyalphaolefin (PAO) base stock ranges from 15 to 40 wt. % based on the total weight of the gear oil composition. 
     
     
         4 . The method of  claim 2 , wherein the synergistic amount of at least a polyalphaolefin (PAO) base stock ranges from 25 to 35 wt. % based on the total weight of the gear oil composition. 
     
     
         5 . The method of  claim 1 , wherein a synergistic amount of at least a polyalphaolefin (PAO) base stock is added to the base oil matrix for the composition to have a pressure viscosity coefficient of at least 16.5 GPa −1  in a temperature range of 70-100° C.