Rear End Oil?

[HvyDty]

I have a 1999 GMC K3500 crew cab long bed. What gear oil should I use 75W-90W? My buddy recommended 85W-140W Valvoline high performance. This is my tow rig so I need something for the high temps in the rear... 14bolt rear end. single rear wheel wheels not duel....

[txab]

Amsoil's website shows Severe Gear 75-140 for the rear. I'd definitely run synthetic

[REV353]

Amsoil's website shows Severe Gear 75-140 for the rear. I'd definitely run synthetic

 

 

+1 Amsoil 75w-140

[jpringle3]

Well I use 75/85 synthetic and the manual says to use 75/90. Using a heaveyer weight oil does not make any sense to me. If it was made to use 140 w oil they would have you use it, it is made to use 75/90

[Nytemare]

What ever you choose...make sure its synthetic.

 

I use Royal Purple. I have good luck with it.

Amsoil is awesome stuff.

 

Both of these are very good at decreasing the temp of the diff significantly. I know the RP will reduce it by 20*+. The AMSOIL will even do better.

 

I would run AMSOIL in everything...but I don't have a dealer where I live.

[Black02Silverado]

Amsoil's website shows Severe Gear 75-140 for the rear. I'd definitely run synthetic

 

The AMSOIL site spec's the Severe Gear 75w-140, which means that is what the manufacture recommends, meaning GM so that is what I would run. Remember this is a 3500 vehicle not the average half ton pickup. Which ever oil you choose I would at least make sure it was synthetic.

[jwhjr]

I'd run the Amsoil too. I have the 75-90 in my half ton.