Information about GM Synchromesh fluid for M5R2 Transmission

kendall221

Registered User
Many say to use the GM Synchromesh fluid for the M5R2 transmissions. There are two different Synchromesh fluids .
Part no. 12345349 (GM Synchromesh)
and
Part no. 12377916 - (GM Synchromesh - friction modified)

Which one are y'all using.

David
 
If you have the stock fiber lined blockers you'll need a friction modifier. So if the price isn't significantly different, you can probably get the stuff with the modifier already in it.
 
I race and constantly speed shift mine. I tried the Synchromesh and found no discernible difference between it and regular old Mercon III with Ford friction modifier. My fiber blockers lasted a year and a half or about 30 race weekends and with Mercon, I get about 2 years. It didn't shift any better with the Synchromesh than with the Mercon III that I'm currently running does. Now, mine is under extreme conditions which yours may not have to endure, but under normal use things may be different.
 
I had no idea there was 2 different kinds. Anyone else know this? I have been using the non-friction modified fluid for about 5,000 miles now too. :mad:
 
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