[noclue]

Have an 03 GT with 68000 miles. Bought it with 60,000 and not sure if I need to change out the rear diff oil. Not sure if the original owner did or not. Do I just remove the cover, let it drain, and then refill to the correct amount? Also are there any additives that you recomend? Do I need a new gasket for the cover too?

[johnr2001]

yes just remove the cover once you loosen the bolts it will start to drain out so have a pan in place. you will need close to 3 bottles of 75/140 or 80/140 gear oil and one tube of friction additive. I never use a store bought gasket.I use the good black rtv gasket maker. run a good bead around and put the cover back on. then remove the plug on the front side of the axle with a 3/8th drive ratchet and refill until it starts running out the fill hole. you may want to wipe the housing out and just check things out while your in there.

[Dave]

I used to like to change the fluid out at 10K miles just to get rid of all the metal bits from wear-in, don't do it anymore. Ford hasn't used gaskets on the rear end for over 25 years, just the black silicone is good. If you don't have LS, wouldn't worry about additives.
Dave