Well heres the thing...i have an 02 wrx tranny, and an 02 wrx rear diff. it grinds 4th gear (from 3d to 4th) at high rpm (4k and up). thing is ive noticed since its getting colder up here in NY it doesn't do it at all. but once it warms up there it is again. next week ill be changing the diff oil with Mobil 1 75W-90 LS. and i was thinking about changing the tranny oil too, i know it takes 3.7 qts. i was wondering if it would be wise to put 1 qt Lucas oil stabilizer, and 2.7 qts of w.e gear oil (no idea what brand). What do you guys recommend i do?