Changing Differential Fluid

[jhm]

Looking thru the owners manual for scheduled service, I noticed nowhere does it say to change the fluid, only check the level. I am thinking of changing both out since the truck has 101K now. Not sure if this would be beneficial. I dont tow or beat on the truck.

[GMCDriver1]

Good point, do NOT use LSD additive in the G80.

[Doug_Scott]

PTFE tape(Teflon tape) may be a better lubricant/sealant for the threads than anti-seize. The plug in the rear end housing is a pipe thread plug, and PTFE tape is designed for pipe thread connections.

[jhm]

before you drain the diffs, make sure you loosen the fill plugs first..it sucks when everything is drained, and you can't refill due to seized plugs..don't ask me how i know

also a lite coat of anti seize compound on the plug threads will help a lot next time..

Good tip. Murphys law!

[Keepontrying]

What brand differential oils are u guys using? is there any additives or friction modifiers that need added for the g80?

[Black02Silverado]

AMSOIL Severe Gear here and you do not need to add anything to the gear oil in a G80.

[txab]

 

 

+1 on everything Nick said

[2017SierraSLT]

I recommend to anyone to change their differential fluids. The factory fill in the differential not only was half a pint low, it was this nasty black crap and it left a residue on everything. I switched to Amsoil Severe Gear 75W90. It took less than an hour and $32. The gasket is reusable. I would drop the spare tire. Makes everything a lot easier to drain/refill the differential.

[GMCDriver1]

Use what weight it tell you in your owners manual. But for my front and rear diff I used regular Mobil-1 75W-90. For the half tons I believe they use a special type of oil for the transfer case that you'll want to get from the dealer. For the 3/4 and 1 ton trucks we get to use regular ATF

[Colossus]

Good point, do NOT use LSD additive in the G80.

We need to have a talk about your image there, ol chap ::glares::

 

Just kidding. Great photo.

[Carder09]

Change it.

[99silveradoz71]

It never hurts to change the fluids out earlier than the recommended intervals if you're planning on hanging onto the truck. I just did mine even though the truck has low mileage due to the age.

[Black02Silverado]

Never hurts to change it, especially if you plan on keeping your truck for a long time. I changed mine out after the first 1,000 miles and then again at 80k right before I went on a cross country trip.

[GMCDriver1]

Every 30,000 is a good rule of thumb, same for the transfer case, or sooner if you do severe driving.

[Gurrzt]

Every 30,000 is a good rule of thumb, same for the transfer case, or sooner if you do severe driving.

+1 on that!

 

When I had Sara's (2001 Z28) rear end rebuilt, I changed the fluid after 500 miles, and then every 30k.

 

in Sara's case I use 85w-140 dyno oil, with LSD additive.

 

In the trucks and SUV I would use 70-90 full synthetic, without LSD additive.

[desrtrat]

before you drain the diffs, make sure you loosen the fill plugs first..it sucks when everything is drained, and you can't refill due to seized plugs..don't ask me how i know

also a lite coat of anti seize compound on the plug threads will help a lot next time..