Syncro worries on fresh rebuilt 833

You must run GL-4 oil in the trans. GL-4 is made for older soft metal (brass) syncro transmissions.
It is getting harder to find, because trannys arent using these type of brass syncros anymore. If you are running gear oil or automatic trans fluid your living in the dinosaur era. Run Red Line MT-90 GL-4 oil, and you will never look back.