I have a 2004 GT with the T-3650 manual transmission, and I still haven't been able to find a clear answer on if synthetic ATF will hurt the synchros over time. Right now I'm running AMS oil synthetic ATF and it seems a little notchy when i first start the car up in the cold. I want my tranny to last as long as possible. For those of you that have a T-3650 transmission what type of ATF do you put in there? Would you recommend switching back to the ATF recommended by the owners manual? Thanks.

 

i just put royal purple syncromax, supposed to be amazing stuff, going with them for my rear when i install the 4.10s sitting next to me in the spring

 

ATF synthetic is fine! Alot of 3650's have the notchy feel when cold just shift slower at first.

 

I trust Tremec, I mean they engineered, designed and built it, I went FROM Royal Purple syn ATF, to regular old ATF

 

Did you notice a difference after you went from synthetic back to the regular ATF?

 

nope, I also did not notice a difference when I put in synthetic when I first got it, IMO there is no point in synthetic in the trans of a 3650, what are you benefitting?? more expensive, eats snycrhos(the weakest link in 3650s)

 

Never heard synthetic eats synchro's??? But definitely try easing the shifts when cold

 

It does in the tko transmissions. The guy I bought my tko from told me to put GM Synchromesh in it, but my trans is a tko. Grey @ the driven man told me that.

 

Thanks for the replies. I put synthetic in so I wouldnt have to change it for a long time, plus all I ever hear is how synthetics are so much better than conventional fluids. I dont understand how the synthetic ATF could eat the synchros or whats in it that would cause premature wear. I was thinking maybe Tremec says that they recommend dextron III because of a contractual obligation.

 

Who the hell knows! Just don't overfill, I believe it's like 3.7 quarts or close to that!