how do you change the gear oil

begin by removing the rear differential cover bolts 13mm and around 10-12 of them, drain the fluid out ....on the inside of the pumpkin there is a small magnet to catch any small debris floating around make sure to clean this off as well. if you have limited slip just drain and refill if not you can use brake clean to clean the inside.....brake clean and clutch packs don't work well together, also you will need to add a modified slip fluid to the fluid if it has limited slip. clean the cover off and reseal with RTV, there is specific kinds, rear diff and trans work best, due to temps and fluid makeup refill to the bottom of the fill plug hole .....test drive and recheck the level after a few miles.