Gentlemen,


Based on some reading I've been doing in the forums, most are finding that their diff oil is pretty ugly--sometimes after only 5,000 miles.


This has me wondering if I should be changing my tranny oil before the factory recommendation (I think it's 25,000 miles). Would it be a good idea to replace the fluid in my Allison and all filters. I have 5,500 miles on my 04 2500HD.


Thanks,


Terel

Gentlemen,


Based on some reading I've been doing in the forums, most are finding that their diff oil is pretty ugly--sometimes after only 5,000 miles.


This has me wondering if I should be changing my tranny oil before the factory recommendation (I think it's 25,000 miles). Would it be a good idea to replace the fluid in my Allison and all filters. I have 5,500 miles on my 04 2500HD.


Thanks,


Terel





Terel,


Of all the years, and there have been a few, that I have changed diff oil, I have never seen diff oil that looked good, especially when you run a posi/locking rear. Even my outboard is pretty dirty when I change it every year.

Terel,


I had changed my engine oil and filter and rear differential fluid at 703 miles. The engine oil looked good, but you could see some very tiny metalic flakes in it. The rear differential fluid had a slight metalic appearance to it and the magnetic drain plug was completely covered with metal debris ( very fine material ) $ 110 for the synthetic from the dealer.


Today I changed the Allison transmission filter at 1,073 miles. Wow the fluid comming out of the prefiltered end of the trasnsmission was dripping into my pan and boy you could see a lot of metal debris. I presently have my oil filter cut open and I am allowing the paper to drain to do a visual inspection of it. I will also be doing the same with the Allison filter to determine how much contaminants had collected in the filter.


I am presently leaving for a weeks vacation to Myrtle Beach, when I get back I will be chaning the oil and filter again, and I will also be changing the tranny fluid and filter at this time ( when changing the filter don't forget the magnet on top of the filter mine was covered in metal debris). I will then go with a 10,000 mile transmission filter change interval and will change to synthetic at this time.


The rear differential will also get changed again after 500 miles of towing, and probably every 50,000 miles there after. I also plan on changing the front differential when I return from the trip which will be about 3,500 miles on the truck. I wasn't as concerned with this as even though it is always turning it isn't a posi and doesn't have pressure being applied unless in 4x4 so the wear shouldn't no where near as high as the rear differential. Dmaxallitech ( Eric ) has an excellent schedule setup for our trucks, but I am just very fussy about the truck and will probably use a modified version of it.


Sorry for the long post, just wanted to pass on what I have seen and my thoughts about a good maintenance schedule.


Best of luck, FranEdited by: 04wanabemax

Change front and rear differential fluid and Allison Spin on ... Reuse ring magnet on the Allison spin on external filter ...

Transfer case check fluid level and depending on usage change accordingly wit lots of use ....Capacity is only a couple quarts...

The Allison under normal condition should be fine at 25,000 miles drain intravels and spin on after initial change at 5000 miles ....

Mac