Rear gear box oil

[Xxl2]

Going to change fulid in my rear axle. I heard JT 7 brand oil was really good. Putting in 75 90 in it. I thought id be swapping the axle but i am not so i ll just change the fulid. I know i should just drop the 10 bolt and get better one. What dose every one put in there the truck is a 91 1500 4.3

 

[Rock Hard Concrete]

Use whatever gear oil is cheapest, and/or whatever will make you sleep at night. It makes no difference. Make sure the second number is 90 that is all that matters.

The weakest point of a 10 bolt is the spider gears. If you do not fry 1 tire while the other one is standing still then it should last forever behind a 4.3. I have blown out 2 sets of spiders in a 10 bolt behind my 4.3 but the bearings, axles, ring and pinion are perfectly fine. Going truetrac next time.

 

[stutaeng]

I think the G80 requires the non friction-modified stuff? Not sure if OP has that RPO code.

 

[Xxl2]

I do not have a G 80 Open diff sorry should have mentioned it

 

[Supercharged111]

New oil is better than old oil. I did synthetic front and rear and haven't seen a difference. I suppose I can now go longer between changes.

 

[Schurkey]

A 10-bolt/8.5" axle isn't worth expensive gear lube. Put in the cheapest stuff you can find that meets spec. Remove the fill plug before you drain it. Some folks can't get the fill plug to come out, then they can't figure out how to put fresh lube back in. (Dump it down the vent tube--pain in the *** but what else are they gonna do?)

GM/AAM has a bulletin on NOT using synthetic lube in certain axles due to the synthetic lube causing deterioration of the RTV silicone sealer used. Some axles can be switched to paper gaskets instead of silicone sealer. I'm thinking that they must have used the crappiest silicone sealer on Earth when building those axles; folks have been usings silicone sealer on axle covers for friggin' decades.

 

[RichLo]

A 10-bolt/8.5" axle isn't worth expensive gear lube. Put in the cheapest stuff you can find that meets spec. Remove the fill plug before you drain it. Some folks can't get the fill plug to come out, then they can't figure out how to put fresh lube back in. (Dump it down the vent tube--pain in the *** but what else are they gonna do?)

I have heard of people filling up ziplock bags with gear oil before they put the cover back on if they cant remove the fill plug. Once the car moves it chews up the ziplock bags and your full again.

 

[Supercharged111]

I have heard of people filling up ziplock bags with gear oil before they put the cover back on if they cant remove the fill plug. Once the car moves it chews up the ziplock bags and your full again.

Works for gasoline too.

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[Schurkey]

I have heard of people filling up ziplock bags with gear oil before they put the cover back on if they cant remove the fill plug. Once the car moves it chews up the ziplock bags and your full again.

Saves on banana peels and hamburger, too.

 

[Nad_Yvalhosert]

I have heard of people filling up ziplock bags with gear oil before they put the cover back on if they cant remove the fill plug. Once the car moves it chews up the ziplock bags and your full again.

Yeah, that's a "trail fix" from our "4x4 and offroad" friends, meant just to get you back to the road and to a shop for a real repair.
Theres still pieces of plastic that WILL clog the oil passages to the pinion bearings, so this tip is not meant for axle longevity