I tried running AMSOIL transmission fluid twice, and both times the sychros wore incredibly quickly, when I took the transmissions apart they were noticeably more "dirty" looking inside, one the sychro snapped in half and ended up breaking some bearings too, and the other deflected out of gear when I was trying to slam it into gear and broke the shifting mechanism inside the transmission. Both had 2nd gear popouts, one after only having the transmission in for a few days. I've been running GM Sychromesh Friction Modified, and it seems to have been working well, transmissions look brand new inside when I take them apart, but I've broken a few diffs at the track and wonder if the fluid has anything to do with it. My car seems to wheelhop a lot though, so that's probably the issue. So I need to figure out what the cause is, because my automatic car with the same exact tires doesn't wheelhop at all.