Has anyone changed the ATF in their 05-up TR-3650 yet? If so, what did you use and how much did you use? The Ford service guide recommends 60k intervals for the manual trans ATF.

After talking with a Tremec engineer, I learned that they recommend non-synthetic Texaco Halvoline Mercon ATF. The owner's manual specifies about 3.17 qt and I recall the 01-04 3650s having significant issues with 1-2 shifts because of overfilling and/or the use of Mobil 1.

I'm a firm believer in the use of synthetics and wanted to know what owners have used (successfully, without any problems) and how much they used. I just bought Rhino Ramps and a siphon pump for pouring in the new ATF.

I was thinking of just buying 3 qt of Mobil 1 ATF. I figure since it is rated to meet Mercon spec, the friction modifiers ought to work with the synchros.

 

If you've had no problems with your manual trans shifting I would use the factory fill specs. Switching to a different fluid might affect the feel of the syncro engagemnts.

 

I switched to Amsoil ATF. Seems to shift better and smoother.

 

I changed out the oil in my tranny at 30k miles to Royal Purple Syncromax. I have to say, the improvements in shift quality (especially 2nd gear) and tranny noise was a LOT more than I expected. It's still not perfect, but it was definitely worth the time and money to change out the fluid.