Cant find 75w-85 gl5 for my diff locally

So i have a 2015 sr5(no rear locker) 4wd v6 manual transmission. I bought it a few three months ago and haven't had much time to even drive it.. im in the process of changing all fluids but getting stuck on the differential fluids. I cant find 75w85 gl5 (manual calls for) locally, what have yall been using. Ive used mt75-90 gl4 for my tcase and transmission... can i use it in both front and rear differentials?

 

75/90 in all three is what I’ve used. Get the cheap stuff unless you’re into heavy duty hauling/towing.

 

I've been using Lucas 7̶5̶W̶9̶0̶. Non synthetic.

See:
https://eastcoastgearsupply.com/ft-2536-ecgs-gear-oil-recommendation.html

*Correction, it is 80W90.

 

Many here use various flavors of

$30 75W-90 Synthetic Gear Lube - 1 Quart (Pack of 2)

75W-90 in lieu of the outrageously priced 85W-90, which as you have noticed is not readily available.
Walmart's Super Tech 75W-90 works just fine.

 

80w90 is fine as well

 

X2 I bought 3 quarts for $24 opposed to 3 quarts of synthetic that would have cost me over $50

 

Gear boxes & diffs- are the best spot to put synthetic (the good stuff) They offer less drivetrain friction loss & the more unified molecules also means the oil holds up longer in these often neglected areas.

 

Lucas 80w90 or 85w140 for added protection

 

I've been using Mobil 1 but that ECGS article mightve swayed me, I've been in the fence for a while due to price. Get two of these and change front/rear and t-case and have left over

$37 Lucas Oil 10046 SAE 80W-90 Heavy Duty Gear Oil - 1 Gallon

https://www.amazon.com/Lucas-Oil-LUC10046-80W-90-Heavy/dp/B000IG5QPK

Our diffs don't need extra LS additives right?

 

Thanks for the comments and extra info. Of course the dealership doesnt carry quarts of 75w85, only bulk. They still aren't going to get my money

 

This isnt rocket science. 75w90 or 80w90. Go to walmart, autozone, etc. They carry it in quarts.

 

GM sells 75w85 in quarts. Part number is 19300457.