Friction Modifiers are compounds that increase the lubricity of an oil. This is achieved by bonding to the surface and forming a low friction layer. When one of the coated surfaces connects with another coated surface the molecules provide a cushioning effect. Common friction modifiers are esters, natural and synthetic fatty acids as well as some solid compounds.
Friction Modifiers are commonly added to engine oils, gear oils and transmission fluids to help reduce wear of the metal components during normal operation.