$38 GM synthetic differential oil.

[ARB1977]

Originally Posted By: brights_garage
Ok I was at the local dealership the other day and inquired about some differential oil for my GMC vehicles. I was told that they had the oil in stock and that it was $38 per quart. I asked why so high and the parts guy said "because its synthetic oil." At which time I replied that so was Mobil 1 at Autozone for $9.

I know this has probably been hashed out many times but does anyone on this site know if Mobil 1 or Valvoline Syn can be safely be used in the place of the GM oil whether LS or not.

Gear oils i wouldnt worry about too much. As long it meets your spec.

 

[Ken2]

Even better, take your own jug to a heavy truck shop and buy some of the synthetic gear oil that meets Eaton's spec for their 750,000 mile warranty.

 

[Jason2007]

I ran Royal Purple 75w-90 in my 06 Silverado w/G80 and never had a minutes trouble.

 

[aquariuscsm]

Originally Posted By: brights_garage
Why do they (GM) only specify their own oil and overcharge for it


It puts sweet moola in their pockets.

 

[ABomb369]

I currently have the M1 75W-90 in the rear diff of my Sierra that specs the expensive "Grape" stuff. Haven't had any issue so far running aftermarket gear oils in my truck.

 

[PW01]

About a year ago, I changed out the rear DIFF on my friend's Trailblazer with M1 75w-90 and he has had no complaints.