I've read "do NOT use Synthetics" and recommendations to use Dextron III ATF but that's always been in the context of the 4L60E's it appears. What fluid should be used in the TH350?
Thanks,
Dave

 

Dextron III ATF is what is used in a TH350; TH400; 4L60: 4L80

 

Sweet! Thanks! My TH350 just got delivered an hour ago. Built for 800hp by Mike Kurtz at Century in Richmond, TX. $2,600 in parts and labor to my old TH350.

 

actually the use of synthetics is highly recommended. i use royal purple max ATF in my th400 ~900hp bbc camaro. the key is the anti wear additives they add, especially good in manual valve body situations where front pump seals take a beating and wear. not to mention the friciton modifiers they add to keep things from slipping, similar to ford type F fluid. i ran type F in my gm trannies before i switched to synthetic. ive noticed a noticeable reduction in wear for sure.