GM SYNCROMESH. TONS OF ANTIWEAR ADD COMPARED TO ATF AND HIGHER VISCOSITY. THE FRICTION MODIFIED VERSION IS MORE SYNCRO FRIENDLY AND WOULD PROVIDE FOR SMOOTHER SHIFTS BUT THE NON FRICTION MODIFIED WILL WORK FINE.
I have been running RP Synchromax for about 30k miles in my T-850 with good results, I have 3 bottles of Pennzoil Synchromesh that I am going to try next though.
Check out THIS thread, about half way down.
I'm currently running RP Synchromax in my SRT-4. It was a huge improvement in shift quality over the ATF+4 + friction modifier that Chrysler calls for.
The GM synchromesh fluid will be a bit thicker than the ATF but it can't hurt to try it.
On that same note, I just picked up some Redline MTL last weekend to try next.
You can get Pennzoil Synchromesh for $6-7 at an auto parts store.
It is a dino fluid, but works great for shifting and wear.
It's just not a lifetime fluid for me.
Redline MTL or Amsoil MTF would be superb for you, as your best options.
If the Amsoil ATF is working good for you I would stay with that, I found in my case I have better shift feel with an MTF. It seems the higher up I go in Viscosity the shifting feels better to a point.
ATF+4 is about 7.5 [email protected] and felt very notchy, Amsoil ATF is 7.6 and was better, then I tried Redline MTF which is 10.6 and it was fine once the fluid warmed up, but cold shifting was terrible. I then went to RP Snychromax MTF which is 7.7 and I am pretty pleased with it, but I am going to try the Pennzoil/GM Synchromesh which is 9.0 and see how that works out.
I use Redlines MTL when I head to the roadcourse for a weekend. For daily driving, the fluid was to thick and shifting was really notchy until the fluid heated up. I dont know how the different fluids and viscosities compare protection wise, but my tranny has always shifted better on the lower viscosity ATF's.
I also tried Amsoils Syncromesh about 45000 miles ago, and it had the same notchy shifting when cold. I had contacted the maker of the tranny a couple years ago, and the rep the responded to my email recommended Amsoils Syncromesh for superior protection and performance. I just couldnt live with the shift quality.
Sorry it's been a while, but I've been busy with work.
Anyway,I went to the local GM dealer and they had the Snychromesh with the FM in it but they wanted $17 a quart!!!
I tried the RP Syncromax but thought it weared down too fast. Anybody else experience this? Wearing down meaning shift quality dimenished within 3,000 miles.
I have tried many fluids, and Redline's C+ATF has provided the best shifting. Not sure which fluid has provided the best protection though. I change my fluid once a year or every 10k miles. With only 2.4-2.6 quarts in the trans, it is farely cheap to change this fluid once a year.
Mopar ATF4 - Factory fill. notchy shifting
Amsoil ATF - Alot better than Mopar, but shift quality started lacking after 5k or so miles.
RP Syncromax - new RP fluid shifting was worse than old Amsoil fluid shifting
Amsoil MTF - notchy right from the get go
Redline MTL - notchy right from the get go, but smooth on the road course after a couple hard laps.
Redline C+ATF - smooth and consistant shifting from the get go. after a few thousand miles, I still have no complaints.
The only fluids that I used the friction modifier with was the Amsoil ATF and the Mopar.