1998 Dodge Ram Van B3500, Chrysler Corporate 9.25" Axle, OEM conventional fill, converted to Amsoil Severe Gear 75w/90 Synthetic.

Noticed the axle leaking from the OEM rubber cover plug. Pulled out the plug to find the diff overfilled with nasty old fluid. I obtained 5 quarts of Amsoil SVG and proceeded to change out the fluid. First step, open the diff:





I cannot recommend enough that you open the diff cover, even to the people who don't have to, because you really get a good picture of the condition of things. Here, you can see that the parts are covered in a layer of nasty crud.





After a good cleaning with brake cleaner, the diff and case are free of the crud, and all old gear oil. You can see that wear on the ring gear appears to be correct, as it does on the spider gears. Not much on the magnet. Just a little metallic mush.

After cleaning and re-sealing the cover, filled the diff up to the proper level with the SVG, and drove. Much less humming coming from the axle, and no leaks at all. Will need more driving to know whether or not there are any mileage increases.

I was glad not to find any bad news back there. This van has a lot of miles on it, but it looks like the rear is ready to go for alot more.

 

How many miles are on it?

 

Well over 100k miles. Probably well well over. Speedo stopped working at 99185, and I am working on getting it running again.

The fill I just did should be good for 400,000 miles. That's about average based on used oil analysis from other vehicles. Guess I won't be seeing the inside of that thing for a while, unless I decide to pull the trigger on a Mag-Hytec cover.

 

Did you use the cover pan seal material specified by Mopar? The problem is that the synthetic material will actually breakdown the typical sealant used. Hope this helps and prevents you from visiting the rear once again in a few weeks.

I had done mine a few months back. Same rear on a 2001. Used RedLine 75W90 synthetic with friction modifier. This is basically the Mopar stuff.

Over the 85W90 that is typically used from the factory, Chrysler issued a TSB for using the 75W90 synthetic with friction modifier for better MPG.

 

I used regular old Permatex Black. Never had a problem with any synthetic oil eating through it. I didn't use any friction modifier, because I have an open rear end. No diff clutches to worry about.