Ok so I'm going on my 4th, yes 4th, transmission rebuild on my 1989 sc (full bolt ons and some extras) and I am going to all brass synchros since my 3rd is going bad (fiber blocker ring). I personally like the feel of the brass synchros on 1st 2nd and 5th gear. So I'm replacing the 2 fiber ones with brass again. I blew the original brass ones (after 1st rebuild) on 3rd and 4th out racing because of a bearing failure. Had to replace with my old fiber ones. At any rate. I'm going full brass synchros.I read a lot of back and forth talk about what fluid to use. I run atf 4+ from Carquest with about 4oz of Lucas oil additive. (Just my personal mixture. What's the optimum combo of fluid for all brass synchros?