Changing it on your own is as simple as taking the cover off, the fluid will drain out then. Jack up one wheel for a minute or two and then the other for a minute as well to get the old oil out of the axle tubes. Clean all of the oil you can reach out with a lint free rag or towel, the bottom of the case will be filthy inside and that is normal. Clean all of the silicone off of the cover, clean the magnet, and put about a 1/8"bead of silicone on a dry clean cover. I prefer to use the grey RTV, I have had less leaks with it. Put the cover on and snug the bolts down, do not tighten them as tight as you can get them, you will force all of the silicone out. The bolts on the bottom of the diff case (maybe 6-8 of them) will also need some silicone on the threads as the hloes they thread into go all the way through into the oil inside the diff case. You will see the through holes when you get the cover off and everything cleaned. Tighten them so you get an even amount squished out all around the cover. Let the silicone dry for an hour, and snug the bolts again, then refill with oil. When you fill it fill to the bottom of the fill hole, then put the plug in loosely and jack one wheel up as far as you can. Let it down and fill it up to the bottom of the hole for the plug. Then jack up the other side and let it down, refill again. You should be full now. Jacking it up on both sides and then refilling is important, if there is not enough oil in there the axle seals and wheel bearings will not have enough lube on them and you will develop a leak in the axle seal or have a wheel bearing go out. Tighten the fill plug and go. Find a parking lot or wide spot and drive in a figure eight as tight as possible, do 4 or 5 to mix the oil and modifier and to get the new oil into the clutch packs.
Depending on what type of oil you use you may need to add some friction modifier. The amount will vary depending on what oil you use, the synthetic lubes will typically need less or even none as some of them are pre-mixed with modifier for use in a LSD. If you do not have a LSD then you don't need to worry about it at all, just fill it up and drive. If you need the modifier add the quantity needed during the initial fill. If you get chatter from the LSD after the figure 8's then add a small quantity of modifier and do some more figure 8's, if it still chatters repeat untill it doesn''t chatter.
This sounds a heap harder than it really is, it will take you about an hour the first time being very careful to get it all right. Don't be surprised to find that the cover is stuck to the diff pretty well. Be careful to not damage the sealing surface prying it off, if you do scratch or bend it a little just flatten it out and clean up the scratch, no big deal.
Hope this helps.
Forgive me for being lazy, I chopped this out of another post I replied to. Just silicone on the cover is fine, if you make a paper gasket and glue it to the cover you will have a much easier time getting the cover off and cleaning up at the next change. If you are in PA and want Amsoil give MGM (Gene Mohney) an email or a call, I think his number is on a link in his sig.
Hope this helps.
Attention: TDR Forum Junkies 
