This question always sparks a debate. Its like the "what motor oil should I use" question

I can say through experience that when we ran a 727 in the race car it really didn't care what fluid was in it. We ran Type F, Dex/Merc, ATF+4, John Deere hydraulic oil, Universal ATF etc...….etc.....etc...… The trans really didn't seem to care. It always performed well and always looked good when we would tear down for inspection and freshen. The last 727 we ran went for 6 seasons (over 750 1/4 mile passes) and still looked good inside when we tore it down. I think having good internals and proper assembly and clearances is much more important than the type of fluid.