Tranny fluid?

**Black02LS1** · 05-13-2007, 12:04 PM

i have been planning on draining/ refilling my tranny fluid and i have a question on what to fill it back up with?...should i use the factory Mercon III ATF, A Synthetic ATF, or GM Syncomesh?...Ive heard some people say that synthetic isnt really good for it, and that syncomesh doesnt lubricate well untill its warm...Any opions would be appriciated!

**blue02Z** · 05-14-2007, 04:35 PM

well first off you dont have Mercon-thats FoMoCo. i put Amsoil synthetic unervisal ATF in mine. do you have a stick shift? how many miles do you have on your car and fluid?

**Black02LS1** · 05-14-2007, 05:30 PM

Originally Posted by blue02Z

well first off you dont have Mercon-thats FoMoCo. i put Amsoil synthetic unervisal ATF in mine. do you have a stick shift? how many miles do you have on your car and fluid?

Its an all stock T-56. it has 53k miles on it...miles on fluid are unknown....at least 11k on it.

**stanger88** · 05-14-2007, 07:11 PM

I run the GM fluid from the dealership. OEM fill. I had put Valvoline Dexron III in it at 75K miles and it shifted like ass. The OEM stuff has smoothed it back out.

**blue02Z** · 05-15-2007, 03:46 AM

any gm compatable atf would should work. i would go with synthetic tho. it keeps stuff cooler and protects better

**stanger88** · 05-18-2007, 05:55 AM

Originally Posted by blue02Z

any gm compatable atf would should work. i would go with synthetic tho. it keeps stuff cooler and protects better

T56 rebuilds recommends Mobil 1, but keep in mind, this IS a shop that fixes tranny's. I just run the GM stuff. Never had an issue with it and GM would want the fluid to be as good as possible so they dont have to put a new $2500 tranny in for all the extended warrenty guys. THAT is losing money.