The problem starts with some of the older manual transmissions using gear oil as lubricants. Newer manual trannys use ATF. With synchromesh it should be fine as long as its not too thick and can get into the synchros and tight tolerances.
I just bought 4 quarts of it too and wainting on my shifter gaskets to put the oil in. On the bottle it does say synchromesh. I can almost guarentee its thicker than ATF, which is why you shouldn't use thicker oils in a manual. However it does say synchromesh and formulated for MT.
With so many people using it, I think a don't do this would have been posted if people where having trannys fail due to running it. Who knows, I plan to give it a try unless someone has a horror story from doing so.
I just bought 4 quarts of it too and wainting on my shifter gaskets to put the oil in. On the bottle it does say synchromesh. I can almost guarentee its thicker than ATF, which is why you shouldn't use thicker oils in a manual. However it does say synchromesh and formulated for MT.
With so many people using it, I think a don't do this would have been posted if people where having trannys fail due to running it. Who knows, I plan to give it a try unless someone has a horror story from doing so.