Changing rear diff. fluid

When I went to my dealership to get my windows fixed, they recommended changing the rear differential fluid, but wanted $149. This was already on my to-do list, but how hard is it to change the fluid yourself? I thought all you had to do is unbolt the fill plug on top so it drains faster, and unbolt the drain bolt. then re-fill, kinda like changing oil... does it seem too easy, or is that all there is to it? also, where do I get the synthetic fluid, what brand, how much, etc...

thanks in advance, John

Gotta pull the pan off the rear end. Clean it up real good when you're done so it won't leak. GM uses silicone now to seal the rear cover. I still use a paper gasket and never get leaks. The best way to change the fluid is to park it pointed uphill so the fluid drains out of the pumpkin. I usually get a spray can of brake cleaner and wash down the insides of the casting to get as much old oil and trash out as possible. $149 to change rear end lube? Damn, I'm in the wrong business. Replace with Royal Purple since it already has all the additive in it for limited slip diffs.

http://i83.photobucket.com/albums/j2...M/IMG_3558.jpg

is this the fill plug? I put PB blaster on it, and tried to loosen it, but it's pretty stuck on there, and before I apply too much force, I want to make sure this is what I need to unscrew. oh, and I'm just using the ratchet, cause it fits perfectly into the hole, is this the right tool?

please respond quick, cause I'm working on the truck as we speak, thanks

-John

Yep, that's the fill point. I use my air impact with a step down adapter to loosen it.

<div class='quotetop'>QUOTE(RedHeartbeat &#064; Jul 8 2006, 03&#58;14 PM) [snapback]57483[/snapback]</div>

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Yep, that&#39;s the fill point. I use my air impact with a step down adapter to loosen it.
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ok thanks a lot. I&#39;ve got my brother&#39;s air tools, but no air supply :-&#092; so I&#39;ll be using the breaker bar on this one :bash:

I just finished about 30mins ago, so thanks a lot to everyone for helpin me out. it really wasn&#39;t that hard, but I just like to know exactly what i&#39;m doing before I start to undertake a project.

no leaks so far and everything looks good.

thanks again

-John

<div class='quotetop'>QUOTE(RedHeartbeat &#064; Jul 7 2006, 02&#58;19 PM) [snapback]57363[/snapback]</div>

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Gotta pull the pan off the rear end. Clean it up real good when you&#39;re done so it won&#39;t leak. GM uses silicone now to seal the rear cover. I still use a paper gasket and never get leaks. The best way to change the fluid is to park it pointed uphill so the fluid drains out of the pumpkin. I usually get a spray can of brake cleaner and wash down the insides of the casting to get as much old oil and trash out as possible. &#036;149 to change rear end lube? Damn, I&#39;m in the wrong business. Replace with Royal Purple since it already has all the additive in it for limited slip diffs.
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Subject: Info - Rear Axle Lubricant Compatibility and Usage #99-04-20-001 - (06/18/1999)





This bulletin is being issued to inform dealers about the compatibility and usage of the new Fuel Efficient SAE 75W-90 Synthetic Axle Lubricant, GM P/N 12378261 (In Canada use P/N 10953455), with current axles, and with the non-synthetic axle lubricant, GM P/N 1052271 (In Canada use P/N 10950849), for the rear axles on the above light-duty trucks.

just some info, but i dont know about non gm synethic axle lube, i have seen racing 90w synethic not atack rtv. the gm axle fluid is not uasable on a silicone axle, unless you want a leak.
gm synethic axle fluid is &#036;25.00 a quart.
8.5/8.625=2qts
9.5/9.5ld=3qts
10.5=3.5qts
11.5=4qts

well if anything goes wrong, and it leaks I&#39;ll know why, but it hasn&#39;t leaked a drop yet *knock on wood*

<div class='quotetop'>QUOTE(ILuvJDM &#064; Jul 11 2006, 04&#58;06 PM) [snapback]57793[/snapback]</div>

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well if anything goes wrong, and it leaks I&#39;ll know why, but it hasn&#39;t leaked a drop yet *knock on wood*
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i dont think it like droping mentos in a 2 liter of pepsi. the synethic fluid is "good for the life of the axle, under normal conditions". that excludes every single person on this web site. i havent yet ever met up with a single person that fits in the "normal usage" column. i change all the H2 HUMMER&#39;s at 18k. the little girls that drive them have clear fluid like new comming out. the ones that i see out at every hummer ralley (4 times a year) and they drive like a bat out of hell just getting to the 7-11 have what looks like roofing tar comming out. so that tells me that even though its synethic and good for life, it still needs serviced. if you silicone the diff cover, fill it with synethic, then forget about it, that may turn into a leak down the road.