Differential Service

All, I have been researching this and I am almost prepared to embark on doing my Diff Fluid Change. I have the AWD Tahoe LT and I prepared with these items.

$120 worth of Royal Purple Gearmax 75W-90
Permatex RTV Black Silicone

In all my TYF research it has not been 100% clear if there is a GM part for a gasket. So, here is the ??? _ IS THERE A GASKET? Or is the suggestion just to make one with the silicone?

i have 6 quarts and i am ready to do both diffs

Thanks,
BB

I dont know if there is or isn't but I've always just done the RTV silicone on my axles on my vehicles. Silicone is like duct tape... cept you can't make as cool of shit as you would with duck tape...

Rear diff is RTV and very simple to do so don't worry about it. You'll quite enjoy the smell of that old oil hahahaha.

Front diff I've never done one so no idea. GL with that and take some pics.

Pics

Dylan said:

Rear diff is RTV and very simple to do so don't worry about it. You'll quite enjoy the smell of that old oil hahahaha.

Front diff I've never done one so no idea. GL with that and take some pics.

Click to expand...

Will do.

Nasty Smell

Yeah my garage now stinks...but reminds me of old Bel-Ray Gear Oil for my dirtbikes back in the day.

All went well. Front was easy and magnet full of metal. I did not take the Diff apart but did the drain/fill method. I wish I would have had some Cheaper Fluid because there was a good amount of sludge and metal. Old Oil seemed kind of gray/metallic. I would have filled with Mobil 1, driven a few thousand miles and then another fill with Royal Purple. But alas, RP went in. Took a little more than 2.5 quarts Royal Purple 75W-90.

Rear was the scary one but it too was easy. I took off cleaned and actually painted the pumpkin with bedliner paint. Scraping the old gasket was easy and then I followed up with a scotchbright pad and brake cleaner. Reapplied the Black RTV silicone, spread even and thin, covering the holes and re-mounted. I did 15-17lbs of torque in a crisscross pattern. I read that and it seemed plenty tight, but if someone can verify, that would be great.

Rear was actually very clean. The oil seemed new. Oh well, refilled with 3 quarts of Royal Purple 75W-90 Gear Oil. So far....no leaks. Here are some pics.

Nice job.

I did mine a year or so ago, and used some Redline "Shockproof" rear dif fluid.

Wanted to use a syn in the front, but I heard that you should only use the GM approved front dif fluid. Probably BS, should have used RP or some Redline. Does the RP meet the spec called out for the front dif fluid?

Use GM TRACII for the TC though, that's the only one you can use for that.

I have a 2000 LT 5.3L with 106K miles on it at this point.

rdtahoe said:

Nice job.

I did mine a year or so ago, and used some Redline "Shockproof" rear dif fluid.

Wanted to use a syn in the front, but I heard that you should only use the GM approved front dif fluid. Probably BS, should have used RP or some Redline. Does the RP meet the spec called out for the front dif fluid?

Use GM TRACII for the TC though, that's the only one you can use for that.

I have a 2000 LT 5.3L with 106K miles on it at this point.

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I have no idea about spec sheets. I went with the knowledge of this board as my guideline! Watch me get stuck halfway between here and FL asking about how to get my Diff repaired! HA. I wish I had time to do my TC before I take a roadtrip but will save that for my return.

BB

I know this is an oil post but I did both ends just recently. But the front only took 1.6 qrts or so and the rear took 2.5 or so. This was bringing the level up to .250-.500 from the bottom of the hole.
Did I screw up?

No, that is right, the front takes less than the back. And to clarify one other thing, the only TC that requires the GM Auto Trac II is the one with the Auto 4x4. If they have Auto 4x4 of any kind then there are no other choices on the market. There are TC's that came in GM trucks that call for tranny fluid and a few that actually call for manual tranny fluid. The best thing to do when starting out with this project in the future is to have the dealer or someone who can, run the VIN # and find out exactly which TC you have so you get it right.

ktmhans said:

I know this is an oil post but I did both ends just recently. But the front only took 1.6 qrts or so and the rear took 2.5 or so. This was bringing the level up to .250-.500 from the bottom of the hole.
Did I screw up?

Click to expand...

No, that's about right. Front should be 1.75, rear 2.75.

On 4wd's, transfer case is listed as 2.00, but only fits likes 1.95.