Valvoline Dex/Merc is not synthetic. Type F supposedly will give firmer shifts so if that's what you want in lieu of better protection I guess.
I don't understand why this is a recurring controversy, but then I'm no expert.
I use this stuff (dex/merc) in both my 727's. is it the best stuff on the planet? don't know, but the factory and rick Allison at A&A who built both trans told me to use it. haven't had any issues but I don't abuse them either. it's probably like anything else; keep it clean and do proper maintenance.
