Patent ID: 8598103
Filing Date: 2013-12-03
Classification: C10M,C10N

Abstract:
1. A method for improving the fuel economy of large low, medium and high speed engines that reach surface speeds of at least about 3 mm/s and are lubricated by an engine oil by reducing the traction coefficient of the engine oil used to lubricate the engine by employing as the engine oil a lubricating oil having a kinematic viscosity at 100° C. of 20 to 25 mm 2 /s and a base number of 40 to 70 mg KOH/g comprised of a base oil comprising a bimodal blend of two different base oils, a first base oil selected from the group consisting of Group II base oils, Group III base oils and Group IV base oils having a kinematic viscosity at 100° C. of from 3 to 8 mm 2 /s and a second base oil selected from the group consisting of Group IV base oils having a kinematic viscosity at 100° C. of 40 to 150 mm 2 /s, wherein the difference in kinematic viscosity between the first and second base oils in the bimodal blend are at least 32 mm 2 /s, and a detergent selected from the group consisting of calcium phenate, calcium sulfonate, calcium salicylate, calcium carboxylate, calcium phenate/ calcium sulfonate, calcium phenate/ calcium salicylate and calcium phenate/ calcium carboxylate at a total treat level in an amount of 8.2 to 18.4 wt % (active ingredient) with a base number ranging from 40 to 70 mg KOH/g, based on the total weight of the lubricating oil wherein the improvement in fuel economy is evidenced by the traction coefficient of the engine oil employing the bimodal blend being lower than the traction coefficient of engine oils which are not bimodal blends or which are based on only Group I and/or Group II base oils or which contain no Group IV base oils having a KV at 100° C. of at least 38 mm 2 /s.