2nd Gen Non-Engine/Transmission differential fluid change

[BBaumeister]

I searched numerous threads but couldn't find what i needed. I am planning to change rear diff fluid but don't know which dana axle I have hows do I find out. also need to know what fluid and or friction modifier I should use. Do I need a gasket or which type sealant is best. THANKS

p. s. 01. 5 3. 55LS gears

 

[ndurbin]

Is your truck auto or manual, 2500 or 3500? all auto 2500s have the Dana 70, manual 2500s have a hybrid Dana 70/80, and the 3500s have the Dana 80. I believe, I'm sure someone will correct me if I am wrong.



Nathan

 

[Clinton]

Seal the cover with a RTV sealant. I would use the Permatex black or ultra black. Form the bead completely around each bolt hole. Give it an hour or so to cure before filling with lube.



Fluid choice usually sparks some debate around here, but typically the more you spend the better the product. I think the choices are something like 75W-140 and 80W-90 (these numbers are guesses). Look in your owners manual for recommendation. I believe the higher service number is the better choice for heavy loads. Synthetic lubes usually state there is no need for friction modifier, but I've found I still need it to be chatter-free.

 

[Nate]

I put 75-140w synthetic in mine.



Oh you should put some friction modifier since you have a limited slip. Napa carries it.



Just run some RTV on the cover a nice bead around the thing, pop it on, tighten the bolts and fill it up.

 

[Jack in Alaska]

I am gathering the "stuff" to do this very thing. I use RTV Ultra Blue for the gasket maker, Amsoil 80W-90 in both front and rear. Add 2 friction reducer in rear only.

Also doing the 5 speed trans. and x-fer case. The trans. gets the real stuff from Dodge and the x-fer case gets Pennzoil ATF dexron-3. The Dodge service mgr. said any kind of ATF will do but you need the correct gear oil for the transmission.

 

[RobertMiller1]

friction modifier

check the diff fluid before adding additional friction modifier. It will say right on the bottle, as does my 85-140 Valvoline semi-synthetic.



In many cases it is necessary as the basic fluid comes with the friction modifier. It is often harder to find a fluid that does not contain friction modifiers.

 

[JPittinger]

"don't know which dana axle I have hows do I find out"



To really find out, look for the hand stamped serial # on the back of the pass. side axle tube. Then you can reference it in the Dana applications list, which I found on their website. This will tell you exactly what you have. Mine was a Dana 70 U (and its an automatic), which I never even heard of. Its in between the 70 and 80.

JJ

 

[BBaumeister]

THANKS ALL



I think I might use some royal purple 75-140 would I need to add friction modifier. If I do does it matter what modifier I use are some better than others.

 

[redram]

Using the RP MaxGear 75W140 does NOT require any friction modifier as it is already formulated into the product. After you install the oil, find a flat parking lot and do 2 or 3 figure 8's to work the new fluid into the limited slip of the differential.