I read in my Dodge Manual that my Dana 70 calls for SAE 90. I notice from previous post that some of yall don't run straight 90. So which is better ?? I use my truck hard, alot of pulling heavy loads and I use my 4x4 almost everyday in the dry sand of South Texas. So with the heavy usage and the 100 degree days which is the right fluid for me. I have already gone to Dodge and picked up my Mopar Limited Slip Additive just need to get the gear oil. But, which one ???

 

Put in a good synthetic...

I'm running Royal Purple 85W-140 in both my diffs.



Tony

 

In my 2001 service manual it states that if you are going to be using for heavy towing to use a synthetic 85w-140. Why it doesn't come stock with that is beyond me since that is what these trucks are designed to do.

 

Since you're in South Texas you can run the 85W140 year round (try and get full synthetic). Royal Purple and Red Line MTL are highly recommended.

 

I have to agree that a synthetic 85W-140 is the best choice for hot weather and hard work. We changed our dump trucks at work to this gear lube and haven't had to rebuild a diff since. Longer service interval and better protection, what else could you ask for?

 

I run a full synthetic 85W-140 in both axles, and it works fine in the winter, even when the temps dip below zero. I wouldn't sweat using an XXW-140 synthetic gear lube if you live where it get's cold.

 

Hey thanks for all the feedback yall and you are right it doesn’t get cold down here in South Texas. A cold winter for me is a temp of 50 degrees. I put a pure 85w-140 synthetic in today and boy did that fluid need changing it was burned up pretty bad.

 

50 degrees - thats practically a warm summer day where I live (just kidding).

Ive been to South Texas and know first hand that it doesnt get cold down there (must be nice).

Ruralmedic - Ive been advised against using 85W140 in colder climates (below -12 deg C)

 

You may want to invest in the Mag Hytec rear cover for the extra capacity and cooling.

 

[quote author=Dr. Evil link=board=4;threadid=18842;start=0#msg177163 date=1061962236]

Ruralmedic - Ive been advised against using 85W140 in colder climates (below -12 deg C)
[/quote]

I don't know who told you that, but again, "W" represents winter rating, the lube's flow characteristics at 0 degrees F. It's a 140 grade gear lube, but will flow like an 85 grade when cold. Ford's factory fill on Dana 80 rear axles has been a 75W-140 synthetic for years now.

 

yeah that makes sense......I remember reading it somewhere...maybe in manufacturers literature. It didnt sound right to me either.

 

Amsoil 75w140 would fit the bill in your situation.

If your using your truck like a truck, go with heavier stuff.

AMSOIL Series 2000 Synthetic Gear Lube is a race-proven extreme pressure lubricant engineered to meet the severe high-load and high-temperature demands of contemporary race and commercial vehicle differentials and gear-lube equipped transmissions. It provides the superior friction, heat and load control demanded by race drivers, the superior fuel economy required by commercial vehicle operators and the superior performance sought by all motorists.