hardcore302

I've heard everything from thae special sauce to syncromesh to mercon v to havoline dexron 3. to rp. or rp messes with syncros. and all of this from tremec's help line.

i want to do a fluid swap.

what is the latest word on the best fluid for a 3650?

Thakns!

Goldenpony

I'm using Amsoil and it works great. I'm not sure there would be a big difference among any good synthetic ATFs.

Det.FrankBullitt

I hear ya! I called tremec's help line and asked about using royal purple and was told the same as you, that RP would mess up the syncros and to just use what Ford recommends.The rep actually said RP was too slick for the syncros???? I want to go to a synthetic fluid but just can't get a straight answer from anyone.

Nuke

I second Amsoil. Pricey but one of the best...

hardcore302

Thanks!

GTRaider

I found a copy of the Tremec TR-3650 Service Manual online some time ago and it says to use Mobil 1 Synthetic ATF or Dexron III and to fill it to the level of the opening. This manual is for the older version with the Turret style shifter that bolts onto the tailshaft but I imagine it's appropriate for any 3650.

If anyone wants a copy, PM me and I'll send it to you by return e-mail.

Be warned that Mobil 1 Synth ATF smells awful so make sure you don't get it on anything that you would like to keep. It smells about as bad as the friction modifier that you add to a diff case for limited slip rear ends.

moosestang

I've been running the same royal purple synchromax for some 5+ years now. Read the reviews on americanmuscle.com

http://www.americanmuscle.com/royal-...ion-fluid.html

There's one guy on the internet that claims it ate some lining in his transmission http://www.moddedmustangs.com/forums...mendation.html and people answering the phone at tremec are reading from a script. I doubt you are talking to an engineer and last I heard they said they've never tested the stuff, so how would they even know it's too slick.

If it were too slick, does that mean it would pop out of gear? What does that even mean?

SON OF 68

I also use Amsoil. Seems to work well. Didn't notice any difference really. Just wanted a Synthetic in there. It might run a bit cooler, but that's about it.

I have heard that "Slick" stuff about RP as well. However, I have never read anyone who is actually using it say they have problems. RP is probably just fine.

baddog671

Another Amsoil ATF member here! I think it was 3 qts.

FrostByte

I kept having noise when tranny was cold. The colder it was the louder it got. I switched to Royal Purple & now its smooth & quiet. I dont care what hear-say from a competitors brand tech I get. I wont go back to any thing else. Worth the extra $$$ IMHO.