2008 Corvette: recommend a M.T. lube

[JRHAWK9]

As some of you may be aware of, the Tremec TR6060 found in the newer Vettes seem to have some pretty notchy 1-2 shifting when cold. This summer I changed mine out to RP Synchromax and it seemed to help a bit. However it's now getting cooler here in WI and the last couple times I took the car out the 1-2 shift was very notchy and sometimes hard to even get into gear when cold. When it's up to normal temp the tranny shifts beautifully. I was wondering if any of you guys could recommend a lube that may give me better cold shifting while still protecting at higher temps? I have thought about trying Amsoil's ATD stuff, but I read that somebody tried that and it wasn't all that great either on cold shifts. I have been going back and forth between maybe trying Redline's D4 ATF or Mobil 1's ATF, but I have also read that DexIII ATF fluid doesn't offer enough protection for manual trannys. I don't know if I should just keep my RP Synchromax in there or if there is something better suited that I can at least try.

Any help would be appreciated!
Paul

 

[Whimsey]

No experience with your Corvette but RP Synchromax is on the thin side of syncromesh fluids, real close to ATF fluid. I use it in my 2002 F-150. It's great in the winter but notchy in the above freezing temps for me. What MT fluid does GM recommend? As you noted ATF doesn't protect a manual tranny. Your best bet is to use a manual tranny fluid. In my case they recommened ATF only for easy cold shifting and cost savings, not tranny life. For tranny life use a manual tranny fluid with the correct additives, not an ATF.

Whimsey

 

[Bror Jace]

JRHAWK9, your tranny calls for an ATF, yes?

I am no fan of Royal Purple ... but I think you're using the best stuff available right now. A couple years ago, before he shut down operations, I would have heartily recommended the thinnest of Molakule's Specialty Formulations syncromesh fluids. Alas, no more.

Whimsey, I think they recommend ATF because it is thin enough to properly lubricate needle bearings. Not only that, but JRHAWK9's primary concern is cold-weather lubrication so I would NOT go thicker.

 

[JRHAWK9]

thanks guys. Yeah, it calls for ATF (Dex III). I was thinking about going back to ATF, but then read a couple posts on this site. Would Pennzoil's Synchromesh be a possibilty?? How does that compare to RP's Synchromax? I am running Pennzoil's Synchromesh in my Firehawk's T56 with good results.

I remember Molakule's stuff and was looking into some if it awhile ago I think. Why did he shut down?

 

[Johnny]

How much fluid does the transmission hold?

 

[JRHAWK9]

it holds ~4qts. Doing a drain and fill it will only take ~3.5qts.

 

[mechtech2]

I would use the D4 over the Mobil 1 synth ATF.
The Synchromesh is thicker than any ATF, but some version of Synchromesh is what I would use if it were my trans.
Cold shifting? Probably worse with thicker fluid, but there are other factors. Any fluid is thicker when cold.
Wear? Better with a true gear oil, but at very low temps I would take it easy until she gets some heat built up.

 

[NewC6]

I'm using the Amsoil ATF. But to tell you the truth, I only did the changover because I like Amsoil products. I am also using ASL and severe gear also and am ordering their PSF and brake fluid.
I did not notice a change in the shifting but then again, I haven't had any issues and I don't live in a cold climate.
My 08 Z tranny has not exhibited the notchiness that many have commented on so maybe I got one of the good ones.

I think you will be fine with the Amsoil ATF.

 

[Bror Jace]

Pennzoil syncromesh is designed to replace the syncromesh fluid in many FWD GM & Chrysler manual transmissions. It has a cSt of around 9.5 ... about 2.0 more than an ATF ... so it'd be about 25% thicker. I can't see how this would be an improvement first thing on a cold morning.

I think Royal Purple Syncromax is the only ATF-thin fluid with a proper additive package. Obviously, any ATF will work, but (theoretically) one with a greater barrier anti-wear additive package will work better.

MolaKule was not happy where he was (I'm not sure the reason) ... and when he went to move, could not find a new facility to host the blending. His products worked great and I believe orders were substantial ... but it was a facilities issue.

 

[mechtech2]

So shift 25% slower when cold.
Instead of 3/4 of a second, take a second.

 

[JRHAWK9]

yeah, I always shift slower until warmed up. I can also shift at a real low RPM into 2nd until it warms up, as it's fine then. In the summer, it's not really an issue.

There are times that 1 sec won't be enough....lol Some guys on the Vette forum double clutch 1-2 when shifting cold. I tried that and it does seem to help some. The best I discovered was to just shift into 2nd at a low rpm.

 

[Steve S]

The shifting may improve as the miles increase.

 

[AzFireGuy79]

I use Red Line D4 in my built T-56 in a turbo SS Camaro. I really noticed a difference in cold weather shifting and it seems to hold up really well in the heat and with all the HP i throw at it.