It is recommended to change the Allison externel filter at 7500 miles. Is this really necessary at the interval?

Yes... I actually changed mine at 1500 miles on my new truck and boy was there alot of particles in the filter. I am going to be changing mine evry 3000 miles when I do my engine oil changes. This is just how I do things. If your not gonna keep your truck over 100,000 miles, then I probally would just follow the suggested manufacturer process.

First one at 5000 then it's 25000 intravels ....


The filters are cheap although but that's manufactures recomendations ...


I do at 10,000 for the hellofit.... Prolly over kill but gives an over all peek see ,when you cut it open ...





Mac http://www.dieselplace.com/forum/smileys/Approve.gif

Changed mine this weekend @ 5000 mi. There was alot of crap on the magnet.

what is the conventional wisdom at what mileage intervals to change the transmission fluid, or do you change the fluid when you change the fileter?

change it often. It is the cheapest insurance you can have. And it only takes two minutes. Why not!

Is there an internal filter and if so when should it be serviced?

i dont see that anywhere in the book and i aksed the dealer and they said only at 50k and if you pull alot then at 25k.....i have 32k and have never changed anything on the trans......

The manual says the internal filter only needs to be changed on rebuild or internal repair. The original filter only has a screen element. Everytime I have replaced one I get one with a paper element though. I can't see the paper one lasting untill the next rebuild. It should probably be changed regularly if it's a paper one.

Ok, so the external main control filter is simply the fuel filter? I just bought one today the part number is: 29539579.

That part # corresponds to the external spin on filter for the Allison transmission. There are three (3) external spin on filters for your DMax/Allison truck. They are the engine oil filter, the diesel fuel filter and the Allison transmission filter. You can get to the fuel filter by opening the hood and looking on the passenger side of the engine. You get to the other two filters from underneath the truck.





This is from Allison's web site:



<TABLE width="100%"><T>
<T>
<TR>
<TD colSpan=2><A name=105></A>Q. Filters - How many filters are there and when do they need to be changed? </A></TD></TR>
<TR>
<TD width="5%"></TD>
<TD width="95%">A. The Allison 1000 Series™ uses two filters to maintain cleanliness of the Automatic Transmission Fluid (ATF). There is a 'spin-on' filter that is externally accessible and is intended to be changed at each ATF change (see owners manual for recommended change intervals). Current P/N for this filter is 29539579. Because this is a relatively 'high pressure' spin-on filter, it is important to tighten the filter one full turn after the gasket contacts the transmission case. Also, there is a removable magnet between the filter and the transmission housing; care needs to be taken that the magnet doesn't get 'thrown away' with the old filter if it happens to stick to the old filter. Beginning with MY03, GM Truck is recommending that the spin-on filter (filter only; not transmission fluid) initially be changed at 7,500 miles. Following that, the filter and fluid should be changed at the recommended intervals.


The other filter is inside the transmission oil pan, and is intended to be changed only in the event of an overhaul.</P? td <> </TD></TR></T></T></TABLE>


Edited by: Darin Billing

Thanks! I was right.