Engine/Transmission (1998.5 - 2002) Rear Axle questions- Fluid changes

[DaveN]

Well, I've decided to go to synthetic on my axles, especially since my POS factory gasket job is leakinglike a sieve. I have some questions -



1. What is the capacity of the rear axle on a 2001 2500?



2. I know that they recommend changing standard gear lube every once in a while to minimize water build up, do you have the same problem with synthetics?



3. Is all synthetic compatible with the axle seals? I. e. if I install brand X will it eat up my seals?



4. I heard someone say something about "rocking" the axle to get all the fluid past the bearings - is this necessary?



5. Recommendations on fluid type?





Thanks in advance for any replies-



Dave

 

[BSeitz]

Just changed mine last week for the first time at 40,000 miles. I'm pretty sure that the stock capacity is four quarts. As for the water build up in the synthetic or the factory gear lube, I don't know. I have not heard of any problems with synthetics eating up the axle seals. I am using the AMSOIL SERIES 2000 75-90w. I installed a MAG-HYTECH diff cover that changed the capacity from 4 to 6 quarts. The AMSOIL rep. told me that the series 2000 already has friction modifier, but it was recommended to me that I use 1 1/2 bottles of the MOPAR friction modifier for 6 quarts and only 1 bottle if re-installing the stock cover. As for rocking the axles to drain more oil, everybody said it was a waist of time and they were right! I jacked up both sides for about 1/2 hour a side, and nothing more cam out. Hope this info helps a little.

 

[jwilliams3]

Dave,

If you have an automatic 3/4 ton the capacity of the Dana 70 should be about 3. 5 +/- quarts. For a 3/4 ton manual with the Dana 80 hybrid 5. 5 quarts +/-

I would suggest either Durablend Valvoline 85w140 or Mobil One full synthetic I think its 90w150 (if I remember correctly)

either one of these brands is about $5-7 a quart and will last a good 50,000 miles In my opinion.



If you have a Napa around you might be able to get a differential gasket for your Dana 70, good luck on the 80 gasket.

You can use Permatex RTV high temp sealant as a gasket, or in combination with a Dana Gasket either way works fine, make sure to get a little permatex in the screw holes to seal up well.



Also if you have limited slip, use some Trans X additive, about 3/4's tube for the 80 and half for the 70.



These have worked great for me and I have changed fluids on both style differentials.

With success.



--Justin

 

[Pit Bull]

Dave, do a search on rear diff lube, there are a bunch of threads covering the change and the different types of lube. I just changed mine and got a lot of good advise from the members. We had a big discussion about MT-1 and GL-5. I used Mobil 1 Full synthetic 75w90 in my Dana 80 along with 2 bottles of friction modifier. Another big discussion on friction modifier and how/how much to add. About how often to change, depends on how you use your truck.