Polymeric surfactants for improved emulsion and flow properties at low temperatures

A method for maintaining a fluid viscosity of a lubricating composition contaminated with water and/or fuel when measured at a temperature of about −30° C., the method comprising adding to a lubricating composition an additive including about 0.1 weight percent to about 0.4 weight percent of a polymeric surfactant with non-polar moieties and about 15 to about 30 weight percent of polar functional groups effective to maintain a fluid viscosity of the lubricating composition, water, and/or fuel as evidenced by a measured flow point of about 25% or less when the lubricating composition is mixed with water and/or fuel contamination and when measured at a temperature of about −30° C., and wherein the polymeric surfactant has a weight average molecular weight of about 40,000 to about 450,000 and wherein the polymeric surfactant is a copolymer obtained from reactants having ethylenic unsaturation and being functionalized either through grafting of polar groups or by incorporation of polar co-reactants in the polymerization and wherein the reactants having ethylenic unsaturation include alkyl (meth)acrylates having an alkyl chain length of 1 to 20 carbons providing the non-polar moieties and the polar functional groups include n-vinyl pyrrolidone or dimethylaminopropyl (meth)acrylamide, and wherein the polymeric surfactant has about 30 to about 40 weight percent active polymer and has a KV100 of about 500 to about 1300 cSt.