Development of Automatic Transmission Fluids Having Excellent Low Temperature Viscometric and High Temperature Oxidative Properties

The development of next generation automatic transmission fluids (ATFs) is described, in which HydroTreated basestock blends of 60, 80 and 160 Neutrals are compared with fully synthetic and partial-synthetic blends.

New ATF formulations are described using both complete performance additive packages and various performance additive packages but with different Viscosity Index Improvers (VII). The VII component can be optimized to be synergistic with the unique properties of the basestocks to provide optimum performance.

This work demonstrated that an all HydroTreated basestock blend can meet Original Equipment Manufacturers' proposed new low temperature Brookfield viscometric properties (20 000 cP max. @ -40°C) and provide excellent high temperature oxidation resistance.