my 4th gear has problems goin in smoothly at a higher rpm, at 50 or 60kmh is i nessle her in its goes fine, but at like 100kmh it grinds a bit, so im wondering, in a ys1 tranny what oil do i use? 5w30? and is gm synchromesh friction modified the same 5w30? what other synchromesh friction modified oils are out there that are compatible? thanks guys merry christmas