I just swapped out the M1 out of the tranny cus I heard of the problems it causes. Good thing it was only in there for like 130 miles or so. I put conventional Valvoline in cus thats the stock fluid. I wasnt sure on the synthetic cus I couldn't find anything on the bottle about friction modifiers which I hear that screw up the synchros. I needed to change it and my school, UTI, only had 80W-90 on hand, is that alright that i put that in instead of 75w-90. Please say it is, i dont want to waste more money with fluid. It has 87k miles on it and would it be better with Uncle Scotty's cocktail or just let the Valvoline ride? I plan on swapping out the engine and tranny for STI parts, when I have the money and/or find the connections for parts. Let me know if I'm good to go.