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2015 Suburban 4wd. 

 

Why is there two different viscosities of gear oil for the differentials?

 

Owners’ manual says 75W-90 (10-416 Synthetic Axle Lubricant) in the front and 75W-85 (10-4091, Rear Axle Lubricant High Efficiency) in the rear? Any idea why?

 

Any reason not to use Mobil 1 75W-90 (Synthetic Gear Lubricant Limited Slip) in both?

 

 

Edited by cs15dah

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Nope 75w-90 is fine for both

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front axle is open diff, rear axle is gov lok posi shit

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1 hour ago, cs15dah said:

2015 Suburban 4wd. 

 

Why is there two different viscosities of gear oil for the differentials?

 

Owners’ manual says 75W-90 (10-416 Synthetic Axle Lubricant) in the front and 75W-85 (10-4091, Rear Axle Lubricant High Efficiency) in the rear? Any idea why?

 

Any reason not to use Mobil 1 75W-90 (Synthetic Gear Lubricant Limited Slip) in both?

 

 

 

Limited Slip 75w90 would not be recommended as it has limited slip additive, which if you have the locking rear, is not recommended to be run.  75w85 is a fuel economy oriented gear lube, and that's mainly why they switched to it. 

 

Long story short, whether you get 75w90 for both, or the right stuff for the rear, use no additive. 

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Alright, then I’ll order the two different weights.

 

3 quarts each for each differential should be enough?

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33 minutes ago, cs15dah said:

Alright, then I’ll order the two different weights.

 

3 quarts each for each differential should be enough?

2qts for the front and 3 for the rear. 

The rear takes just a little over 2 qts.  The front just shy of 2 qts.

Edited by Black02Silverado
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Done. Thanks for the help, fellas. ACDelco’s 75W-90 in the front and 75W-85 in the rear. 

 

Also did the transmission and transfer case fluids, since I was already underneath the truck this weekend. I’ll eventually get around to dropping the trans pan and do the filter at another time. Used Valvoline MaxLife. Next time I’d like to go with the new Mobil 1 fluid being discussed in the transmission shudder thread. 

Edited by cs15dah

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