Hey guys,

I have an 01 ram 1500 4x4. Can I use 75w90 in my rear differential without any trouble? The parts store guy gave me this Mobil 1 ls fluid. Now I'm being told 75w140 by another dodge owner. Am I ok to use 75w90 with the ls additive

 

Should be fine. If you do a lot of towing/hauling though, I would trade it in for the 75w140.

 

I never tow or haul anything. It's just a second vehicle. I don't want to burn anything up though

 

I put in the 75w90 in my rear differential of my 2001 ram and the truck runs good, no issues. Has anybody else run 75w90 long term? The fluid had never been changed in 115k, it was disgusting

 

I am thinkin' that clean fluid, that actually lubricates, regardless of weight, is going to be better than what was in there....

 

Should be fine, especially if the Mobil 1 is synthetic.