Well, I tried Lucas 85w 140 oil and same issue; shifts perfectly after sitting for a while but grinds increasingly as the transmitting temperature rises. It's gotta be the synchro. Of course, I plan to do a complete rebuild while it's being replaced. Going to replace both the 2nd and 3rd gear synchros. I'm having trouble finding the right kit with the synchros. I'm seeing a lot of references to M20, M21, M22 and I don't know what that means. It looks like all the kits I find are for the later SM-318s but I can't be sure. Anyone have a good source for a rebuild kit with synchros for the earlier SM-318 transmissions?
Thanks
