Gear Oil synthetic

How many qts of gear oil does the 03 Denali take??
I ordered a rear cover gasket and gear oil from my GM dealer. and he sells me 6 qts of the pricey GM Synthetic gear lube !! $16.00/qt, were talking $100 worth of gear oil !!

can I put this in the front diff too ??

I still can't see 6 qts !!
how many qts should I return ?

You can get Mobil 75w90 at autozone and penzoil
at walmart. Both for less than $7

How many qts of gear oil does the 03 Denali take??
I ordered a rear cover gasket and gear oil from my GM dealer. and he sells me 6 qts of the pricey GM Synthetic gear lube !! $16.00/qt, were talking $100 worth of gear oil !!

can I put this in the front diff too ??

I still can't see 6 qts !!
how many qts should I return ?

I used castrol synthetic and added limited slip stuff from dealer. I think about 2 1/2 liters went in

Denali's don't have limited slip.

Denali's don't have limited slip.
Correct. I am a new user and thought that my vehicle stuff showed on a post. I have a 97 yukon
markdpro