Rear diff gets real hot

[Black91TSiAWD]

Ok, I started getting a humming/rumbling on decel from my rear end. So I swapped the fluid out for some new stuff, noise went away for the most part so all's good there. Now I never checked the rear before to see if it was hot or not before this, but after a 25 mile drive on the highway I decided to check it. This thing was pretty damn hot, I couldnt hold my hand on it for longer than 4 seconds. Im pretty sure that it isnt normal to be that hot.


Im running all the same size tires, dont have lsd, and replaced with some Napa brand 80-85-90 GL-5(.9 quarts)and all the other numbers that matched my haynes book.

Basically, Im asking what would be making my rear diff get so hot? Or am I way off-base and should it be that hot?


I searched too but came up empty handed. Thanks

 

[loweperf]

Given the temp alone I would not be concerned but put it together with noise and you could have problems. A 25 mile trip will get the rear fairly hot 120-150 deg. I would just keep a ear open for the noise to come back.

 

[Awdboost]

I would us red line shock proof gear oil. Nothing elses.