Thank you so much for that info. I will DEFINITELY try it. After 4 repair attempts and a wholenew rear end, I STILL have whine on decel from 50-40 mph. I'll call it mild - like a flutter. I hope to god this works, 'cause I'm tired of visiting the dealer.
I've never messed with diff before - is it fairly easy to do?
It is a little more complex than a normal oil change, but it's not that bad. The annoying thing is that the factory diff cover doesn't have a drain plug. That means you have to remove the cover in order to do the work.
RTV silicone sealant
Brake cleaner spray
3/8 drive ratchet & a short (3") extention
Sockets & wrenches (See below)
Here is the basic procedure:
1) Block the front wheels for safety. Then jack up the rear of the car and support with jack stands under the frame.
2) Support the rear axle with the jack. Then, unbolt one end of the panhard bar. (I suggest the lower end where it meets the axle at the Drivers's side). Swing the panhard bar up and out of the way and secure it there with a piece of cord or some zip ties or something like that.
3) Lower the jack so that the axle comes down and you can access the cover. Make sure the panhard bar is out of the way.
4) Position a drain pan under the differential housing. There's only about 2.2 quarts of fluid in there, so it doesn't have to be a huge pan. Remove all the cover bolts, except leave the top one loose.
5) Seperate the cover from the housing. You might have to gently pry it with a putty knife. If you have to pry, do it carefully so you don't gouge the cover. Once it pops free, the loose upper bolt will stop it from falling down and making a mess. Once it's free the oil will drain out into your pan.
6) Remove the upper bolt and the cover.
8) Scrape off any residual RTV from the cover and from the diff housing using a razor blade.
9) Clean the sealing surfaces of the cover and the housing with a rag and brake cleaner.
10) Apply a bead of RTV silicone on the cover. Make sure to make a continuous bead and make little circles around the bolt holes. You don't need a huge amount of sealant. A 1/4" bead is plenty. If you need to, smooth the RTV out with your finger so there are no "thin spots". Then put the cover back on the housing and secure it with the bolts. Tighten the bolts gently and in a random pattern so you don't warp the cover. Once they are snug, give them all a final tightening. Don't crank down on them, all they are doing is holding the cover in place.
11) Remove the fill plug, which is located on the forward side of the differential housing. You may have to feel around for it. It's on the driver's side and it points directly forwards. It has a 3/8 square recess in it. Using your 3/8" ratchet and the 3" extension, remove the fill plug.
12) Fill the diff with the new oil until a tiny bit starts to come out of the fill plug. A handy way do to this is a simple pump dispenser you can get at an auto parts store. They have a long hose you can stick into the fill hole and then you simply pump in the oil. Wipe off the excess oil with your rag, and then re-install the fill plug. I put a small amount of pipe sealant on the plug's threads to prevent leaks.
13) Raise the rear axle with the jack and re-install the end of the panhard bar you removed. Then, raise up the car, remove the stands, and you're done.