I am getting ready to pull the diff covers from my truck and use Amsoil for the axle fluid.

My manual states to use 75W-90 for the front AAM 9.25 and also for the rear AAM 11.50.

I understand that Amsoil protects far beyond conventional fluids, but I have also heard about problems with the 75W-90 not being "enough".

I have heard some people stepping up to 75W-110 or even 75W-140.

Anyone have comments or suggestions on the weight suggested by Dodge?

 

Hi,

I went with the 75W 90 in the front and 75W 140 severe gear in the rear.
For my application is was probably overkill as I rarely tow over about 10K.
Next change I am going to the 75W 110 in the interest fuel efficiency.

If you tow at near or at max gvw I would go with the 75W 140.
Good Luck!

Jim B

 

My dealer told me they recommend 75-140 for people who tow. The climate can be quite hot here.

I ran Redline in this truck and my last, with good results. In theory I suppose thicker oil would add drag, but in my experience it made no difference in mpg.

 

Also using 75w-140. Didn't see a change in fuel economy either.

MikeyB