ICQ>

Dexron-II,-IIE,III,et al. have frictional properties that will allow some slip of clutches, bands, brakes during shifts for smoother shifts for a transmission with the appropriate accumulator springs to control pressure build up during shifts. Type F has frictional properties that allow the clutches, bands, brakes to grab, or rather not slip as much, during the shifts and have accumuclator springs that allow the pressure rise to be delayed so as to not be too harsh during low throttle shifts. Dexron-XX in a gearbox laid out for Type F will have excessive slippage and can (for most drivers, will) cause much decreased trans life. Full fill of type F in a box laid out for Dexron-XX can cause abrupt enough shifts so as to shear lining off its metal backing in clutches, brakes , bands though this is really rare. I've gotten rebuild kits that have the frictional parts and seals for gearboxes that span years that use type F into years that use Dexron-xx and they would be the same parts exactly. The main differences are in the valve body and its drilled orifices and the springs used under accumulator pistons. Parts not provided in an overhaul kit.

Many trans shops use to (and maybe still do) use Type F only as the crisp shifts made a customer with a previuosly lazy trans really notice the effects of trans overhaul and some i know said they felt it gave longer service life in typical chrysler and GM boxes used for towing.