Differantial oil

[acres90]

Im going to change the oil in my front and rear diff on my '13 denali AWD. I think im going to use 75/90 synthetic...do i need a limited slip addative?

 

[swathdiver]

Im going to change the oil in my front and rear diff on my '13 denali AWD. I think im going to use 75/90 synthetic...do i need a limited slip addative?

No additive.

 

[Foggy]

Nope.. The rear G80 does fine with GL5 spec gear oil

 

[Fless]

Does the front diff take a different weight oil on these? It does on my NBS.

 

[George B]

Does the front diff take a different weight oil on these? It does on my NBS.

Yes, 80w90 in the front and 75w90 rear.

 

[OR VietVet]

Welcome to the forum and you have the correct answers. Were you going to use the same fluid for both before @George B set you straight?

 

[Onlyone]

I run Amsoil 75w90 in mine, front and back. It won’t make a bit of difference. Make it easy on yourself. Owners manual confirms for my Denali

 

[swathdiver]

Correct, GM has changed the recommendation for the front differential from conventional 80W90 to full synthetic 75W90. This applies to our older trucks as well. Never understood the reasoning for two different fluids, maybe the older spec was quieter?

Limited slip lube in a stock truck G80 causes chattering.

 

[Fless]

Correct, GM has changed the recommendation for the front differential from conventional 80W90 to full synthetic 75W90. This applies to our older trucks as well. Never understood the reasoning for two different fluids, maybe the older spec was quieter?

Limited slip lube in a stock truck G80 causes chattering.

Would you be able to point to written documentation of said change of recommendation?

 

[acres90]

Thank yall for the input. I changed diff oil in my '99 corvette and it said to use limited slip additive, reason I asked. Thanks!