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Rear Differential Oil: Making My Head Spin

pendetim

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pendetim New Member

pendetim

Posted
Posted

I have been in the process of changing my fluids in my 2002 Envoy and finding the correct oil for the limited slip rear is giving me a headache!

 

I started out going to use Mobil 1 75W90, but on some other forums folks contacted Mobil and they said not to use it. Fine, I accept that from the company, thanks Mobile for being honest and upfront.

 

Ok with that off the list, I went back to the owners manual and it called for 4 pints of GM#12378261 meeting spec 9986115 75W90.

 

I called two dealerships and both told me I needed part number 88900401 at $27.58/qt.

 

So, off I went to the closest one. The bottle said: ACDELCO Synthetic Axle Lubricant 10-4016 / 88900401. No where on the bottle did it reference the 9986115 specification or say anything about limited slip friction modifiers. All it said was "heavy duty extreme pressure GL-5 lubricant".

 

I questioned the parts guy and he double checked in his computer and verified it was the right fluid.

 

So I came back home, drained the rear and pumped it in.

 

Now I am really double doubting what I did.

 

Did I just screw the pooch using the wrong stuff or am I just over thinking this job????

Chris Senior Enthusiast

Chris

Posted
Posted

Do you have code G80 or G86? G80 does not require LS additive because it is a locker. The additive could do damage. G86 is a Limited Slip and usually found in cars. It would need the additive

pendetim New Member

pendetim

Posted
  • Author
Posted

Do you have code G80 or G86? G80 does not require LS additive because it is a locker. The additive could do damage. G86 is a Limited Slip and usually found in cars. It would need the additive

I just looked on the glove box door and there seems to be a G80 code there! - along with about 60 others.

Chris Senior Enthusiast

Chris

Posted
Posted

ghe G80 is what matters for your oil. Based on your vin tge dealership parts counter gave you the oil right? If it was incorrect keep your receipt because your vin should be mentioned and they are at fault. Being that they ran your vin code G80 came up and they should have gave you oil that DID NOT have LS additive. You said the lube had no mention of the additive which leads me to think its the right fluid.

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