The invention provides a grease composition for a ball joint which has a low friction coefficient under a load from normal temperatures to high temperatures, a small difference between static friction and dynamic friction, and little change in the friction coefficient even after repeated operation. TO this end, the invention provides a grease composition for a ball joint comprising: (i) a polyisoprene rubber and/or (ii) a polyisoprene rubber viscous material; a specific aliphatic amide and/or a specific aliphatic bisamide; and a specific urea compound.

The invention provides a grease composition for a ball joint which has a low friction coefficient under a load from normal temperatures to high temperatures, a small difference between static friction and dynamic friction, and little change in the friction coefficient even after repeated operation. TO this end, the invention provides a grease composition for a ball joint comprising: (i) a polyisoprene rubber and/or (ii) a polyisoprene rubber viscous material; a specific aliphatic amide and/or a specific aliphatic bisamide; and a specific urea compound.

The present invention relates to the field of lubricant, and specifically provides a lubricant composition and its preparation method and use. The lubricant composition comprises a base oil and rubber particles having radiation crosslinked structure dispersed therein, wherein the base oil is continuous phase and the rubber particles are dispersed phase. The viscosity of the lubricant composition of the present invention can be effectively adjusted as temperature changes. As compared with the lubricant composition comprising chemically crosslinked rubber particles, it has a lower viscosity at low temperatures and a higher viscosity at high temperatures, and has a relatively high viscosity index, which can meet the application requirements at the temperature above 200? C. In addition, the lubricant composition of the present invention also has excellent antiwear and friction-reducing properties.

This disclosure describes a method of improving fuel economy of an engine. The method involves lubricating the engine with a lubricating oil composition that includes a) an oil of lubricating viscosity; and b) a viscosity modifier including an olefin copolymer or diene-based copolymer or homopolymer wherein the viscosity modifier has shear stability index of 15 or less. The lubricating oil composition is substantially free of viscosity modifiers other than the viscosity modifier of b).