i don't recommend using GL5 oil in your transmission, as it can make for notchy shifting(too slick). GL4 is what's called for, redline MT90 is a very good choice. i believe amsoil has a similar offering now, and sta-lube makes 80w90 GL4 oil, but it's not much less expensive than the redline synthetic(6 bucks a quart vs 7.99)