Lots of racers use type-F because it will work very good when you have no lock-up converter and you dont have to worry about the car getting hot in the hot summer with the ac and all on. Thats where the Mopar ATF+4 works very good as its a good trans fluid and is the best to use in newer Mopars. In race cars and our hot rods without lock-converters and all the type-F works good where you dont get very hot under hood temps like newer cars and I believe it does not have the slippage friction that newer fluids have that have to work with lock-up converters. So type-F they say has less slipage and works good in the older tranny's. Myself I have a good amount of the Mopar ATF+4 since I worked at a Dodge dealer for about 24 years so thats all I use in mine and it has worked good for me. I have the Mopar ATF+4 in my sons Dart thats used it since 1997 and the fluid is still super clean as it has been changed twice since then. Course its a low milage street car and the same for my 63 as the fluid and trans look like new and the shifts are nice and firm. The ATF+4 has worked fine for me. Ron