Changing diff lube yourself is easy - It will take 5 qts to change out a 4x4, 3 for the rear and 2 for the front. You will have some ...

It will take 5 qts to change out a 4x4, 3 for the rear and 2 for the front. You will have some left over.

You can order it here and get it shipped UPS to your door Severe Gear® Synthetic Extreme Pressure (EP) Gear Lube 75W-90 (SVG)

you forgot to add the 3oz bottle of "fricton modifier" for the limited slip before refilling...

Nope, I did not forget. There is no additional modifier needed for my truck. My understanding is that for this rear end there is nothing else required.

gOt BoOsT wrote:you forgot to add the 3oz bottle of "fricton modifier" for the limited slip before refilling...

GM doesn't offer limited slip diffs in their trucks, do they? I though it was just the G80 locker.

Correct.............. The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.

The only truck I believe that came with a limited slip was the Quadrasteer and it was not coded as G80, G86 was the code used.


Axle
G80 Differential, heavy-duty locking rear
G80 Differential, automatic locking rear
G80 Differential, heavy-duty automatic locking rear
G80 Differential, limited slip rear
G80 Differential, limited slip
G80 Differential, locking, heavy-duty, rear
G80 Differential, Zexel-torsen, limited-slip, rear
G80 Differential, automatic
G80 Rear Axle: Positraction
G80 Locking, Rear Axle
G80 Axle Positraction Limited Slip
G80 Differential, locking, rear
G85 Differential, limited slip
G86 Differential, limited slip
G86 Differential, limited slip, heavy-duty, rear
G94 Differential, full-locking rear

If the diff cover has been on the diff for a while, the gasket tends to stick to the metal. I just did mine. If this is the case it is very important to clean both the diff case an the cover. Use a razor blade and scrape off all remnants of the old gasket on both sides. Be careful to not leave any of the shavings on the actual gears or in the case, wipe and clean them off before re-installing. I also like to use a RTV sealant on the gasket before re-installing.

Mine was not that old, so it came off cleanly. But, I would agree with completely removing and cleaning the old gasket off. As far as RTV, I am not so sure. I made sure both surfaces (diff housing and cover) were completely clean and dry, then but the gasket on. I tightened it like a tire--star pattern. No leaks whatsoever, and no RTV. I did not want any RTV to get in the diff.

I decided to tackle this job today, did the front diff yesterday. I got 3 qts of 75/90 syn and had to order the gasket, it should be here this afternoon, I hope the new one is like Eric's because the one I had to scrape off was a felt like material, PITA! Also I have the magnet in the filler screw instead of on the cover like the one in the pic. The fluid looked good with 48K on it and the E80 looked great as well . I'm going to follow Eric's step in installing with the star pattern and slowy building up enough torque to match what was there when I took off the cover.

Yep, same gasket as in the pic , very easy to install, wish all gaskets were that easy to install. Put in about 2.5 qts, test drove, no leaks.

The star pattern works. Mine has not leaked in 5.000 miles...and counting.