Study of Viscosity Index Improver for Fuel Economy ATF

One very effective way to improve fuel economy of motor vehicles is to reduce the viscosity of the automatic transmission fluid (ATF). However, viscometric constraints often exist for a particular ATF application. The proper choice of viscosity index (VI) improver allows viscosity reduction at lower temperatures, while maintaining viscosity at higher temperatures. This study shows that molecular weight of a VI improver is a key factor to achieve high thickening efficiency, improved shear stability and limited metal fatigue failure simultaneously. Based on this study, an optimum VI improver has been found and a new fuel economy ATF was developed.