Patent ID: 6077455
Filing Date: 2000-06-20
Classification: C10M,C10N

Abstract:
An automatic transmission fluid composition comprising:(a) a natural lubricating mineral oil free of synthetic oils comprising a blend of natural lubricating mineral oils having a kinematic viscosity greater than about 3 mm.sup.2 /s at 100.degree. C., wherein said blend of natural lubricating mineral oils comprises:at least one first natural mineral oil having a viscosity of at least 3.8 mm.sup.2 /s at 100.degree. C.; andat least one second natural mineral oil having a viscosity of less than 3.8 mm.sup.2 /s at 100.degree. C. and a viscosity index of at least about 90;(b) a plurality of viscosity modifiers having an effective molecular weight from about 50,000 to no greater than about 175,000 atomic mass units; and(c) from about 0.01 to about 5 weight % of a friction modifier; provided that said composition has a -40.degree. C. Brookfield viscosity no greater than about 18,000 centipoise and the difference between the new and sheared viscosity of the composition is no greater than about 0.30 centipoise when measured at a temperature of 150.degree. C. and a shear rate of 2.times.10.sup.2 sec..sup.-1.