I am getting ready to go buy some Amsoil diff fluid.

I know the stock calls for 75W-90, but has anyone felt how hot the stock diff cover gets?

I was thinking about moving upto the 75W-110 weight.....

Also, how many quarts will I need for the rear, with a Mah Hytec diff cover?
Stock is 7.6 pints, but how much additional will I need for the MH?

 

Not sure about the capacity with the Mag but the 75/110 would be just fine. I am running the 75/90 and after a good tow I did check the diff by hand and it was hot to the touch but nothing that I felt was too hot. This is during the hot summer months here also.

 

I am running the 75w110 in both my diffs and think that it a good trade off, not too thin like the 75w90 and not so heavy like the 75w150. I can't remember exactly but with the front and rear MagHytec diff covers I was just under a case for both. Like 11.5 quarts, but I can't remember them each.

Dustin

 

If you do a lot of towing you might want to consider the 75w140 Severe Gear. Otherwise the 75w110 Severe Gear is good to go. Out here in the HOT desert SW, most run the 75w140 Severe Gear regardless of whether they tow or not. That's what I'm running. I think it's 16 pints for the rear and 9 pints for the front with the MH covers.

CD

 

I run 75W140 (Redline) at the suggestion of my dealer. There have been a few times I've towed in 110+ temps, up a really long 6% grade...

 

I used to run Amsoil Severe gear 75/140. I was towing a lot and never had a problem.

 

On my 2006 with the MH diff cover I out in just shy of 8 qts

 

What Weight Diff Fluid ???
Use some that weighs about 7.5 # / gallon.
Any quality GL-5 syn lube in 75- 90/140 range will work fine. If you tow go for the higher last number.

 

Your differential will run a bit cooler with 75W90 than it will with 75W140 or 75W110. The thicker oil causes a bit more friction and heat.
The AAM differentials came factory filled with non friction modified oil so if you're running a Trac-Rite you may want to stay away from oil with friction modifiers.
Billy

 

As mentioned above thicker is not really better if it is heat you want to avoid. Just make sure it is full synthetic (as Dodge recommends) and you will not have to worry so much about heat..

 

I usually run the 75W140 in summer and then the 75W110/75W90 in winter I do tow a lot and heavy and havent had any issues.

 

another fan of the sever gear 75w-110 in the rear and 75w-90 up front...