I did it once...but Bob Hanlon warned me about using it in another other than summer weather. Sure enough, a couple cold mornings did one T5 in. If you want to use Redline, go for the D4ATF stuff.
I guess I need to do a dreaded tranny fluid change. Being that the temps never dip b elow 65 here in Hawaii gives some leeway I guess. Thanks for the head's up.
i have heard similar things in regard to what 89GX mentioned.
it is not nice to needle bearings. i was thinking of goin the same route as you did (using MTL in the stang) - i live in Tucson and thought the same, given the high temps.....but Redline said that D4 was made just for that application. i asked if i could run the MTL or a mix and they said they did not recommend it.
my eclipse calls for 80/90 GL4 in the transaxle. many folks use a mix of MTL and MT90, the former being a little lighter in viscosity. but i think MTL still equates to something like a 70-90 weight gear oil..... i would worry about it flowing into the needles....
please know that im not saying that this is bad and your trans is gonna take a poo with the MTL in it. but, i would hate for you to run it and have problems, and say "why didnt anyone say something."
i dont see why trans fluid swaps are so tough. i have several feet of clear plastic tubing from the home store. i pop the hood and feed it down the pass side to the trans fill hole. stick it in the hole, and fill from up top. works for me.
good luck and please dont take offense or take this as criticism - we are all here to learn and help.