I've searched this forum and it seems everyone uses different fluids for their T-5's. I have a 1990 lx 5.0 with a 5-Speed ( I think that's the T-5, correct me if I'm wrong) and I'm about to change the fluid. The manual asks for mercon but people have suggested using Royal Purple Synchromax, GM Synchromesh, Redline ATF, Mobil 1 Synthetic ATF etc... So what's the best stuff to use for the smoothest shifts and best protection? Thanks!