There is two versions of GM Synchromesh, you want the friction modified version with the part #12377916. If you don't use that one then you may not see any change in results from regular fluid. We used to use the other one (#12345349) in the race cars and in the last couple hours of a 13 hour endurance race we would develop a slight grind in 5th gear, the friction modified version prevented that from that point on.


Friction Modified




Not Friction Modified