Originally Posted By: 69GTX
Originally Posted By: dailydriver
Originally Posted By: 69GTX
My '99 Tremec T56 6 speed is spec'd for Dex III. I use the same Valvoline DEX/Merc blue bottle shown above. Some of the components in these earlier manual transmissions don't sit well with synthetics
or the newer DEX 6.
The last line above is up for discussion/speculation, as some EARLY,
pre-carbon blocker ringed, T56es (even the Borg Warner produced ones) have had NO blocker ring/synchro problems using either a synthetic Dex 3, OR a synthetic MTF.
The bolded above is not just correct, but I will add that a Dex 6 ATF should NEVER EVER be used in a T56/TR6060 (and probably not in ANY Tremec/NV manual which calls for an ATF).
That's exactly why I stated "some" T56's. Earlier versions (like my 1999) are incompatible with some synthetics, syncromeshes, ATF 6, etc. Even Tremec themselves only recommends ATF DEX III and Mobil 1 synthetic ATF as the only approved/verified oils for the 1998-2002 T56's. Not sure how many years beyond that it might go. I have no intention of ever using anything but those 2 products in my T56. And my fill plug is labeled with DEX 3 only. All those other products have an increased "risk" of being incompatible on "some" T56's. Considering that 3 of the 5 years that the 4th Gen F body was produced have cellulose in the blocker rings (1998-2000), that's a significant number of T56's.
At least part of that "speculation/discussion" I noted is BECAUSE Tremec ONLY actually tested those two 'recommended' fluids you've mentioned in your post, and NO others (either in the earlier cellulose composite blocker ringed models, OR the latter carbon lined blocker ringed boxes).
I have used full synthetic/high POE content base stock, Red Line D4 and MTL in my late 1999/
early year 2000 built, cellulose composite blocker ring equipped, T56
for almost it's entire 16 year/180+K mile life and have had NO/0 problems with this gearbox.
Others, even those who abuse their gearboxes even more regularly than I with even MORE racing/road course use, have had similar results using high POE/group 5 content base stock fluids in their T56es.
