Hello, i am going to install a tru cool 4590 transmission cooler on my th400. i am also going to change the filter and fluid. anyway i would like to put in amsoil synthetic atf but at 11.50 a quart its mighty expensive. i was wondering what you guys think is a quality alternative i can buy at walmart or autozone and places like that. i like valvoline dex/merc but something like mobile 1 atf if its not to expensive is better. i would like to stay at or below $7 a quart. what is the difference between valvoline dex/merc and valvoline maxlife dex/merc. thank you.