What kinda fluid? how do I know when it's going bad?

[Rockinlittle325i]

well I bought some fluid for the ol' 5 speed today, but the recomended stuff stuck me as odd
75w 90 synthetic gear mobil 1

should I use it?
what happens when the transmssion starts going bad?

mine is producing a bit of heat I can kind of feel at my shift boot (or it could be my exhuast cause I have no sheilds)

what do you guys use?

[jlevie]

I use Redline MTL. Or a quality synthetic ATF if I don't have any MTL handy.