Allison Transmission fluid change

[jmcgmc03]

I have a 2003 GMC Duramax with the Allison transmission. I am going to have the fluid changed soon and I am considering using a synthetic trans fluid. My question is this: Is there a screen/filter inside the transmission pan, even though it has the external spin on filter? I intend to use Amsoil trans fluid. Are there better fluids out there that you would recommend? What does a fluid change cost? Any advice would be greatly appreciated.

2003 GMC D/A CC
Polo Green
:confused:

[jjackson]

jmcgmc03 - There is a screen inside the pan, but I beleive it is recommended to be changed only at "transmission rebuild" time, but you might want to contact a local Allison rep to confirm.

I have used Amsoil products for years, but I seem to recall a few comments on The DP that some folks might have experienced some "slipping" with Amsoil Syn Trans fluid under certain conditions.? I actually had a case and was going to use it but have since decided to go with the Transyn that Allison recommends.

John

[jbplock]

jmc,

Yes there is a filter inside the Allison Pan, but (per Allison) it only needs to be changed if the transmission is overhauled. However the external spin-on filter should be changed periodically. Many folks here have changed the internal filter when adding a larger pan as the deep pan requires a different filter with a longer neck. A change to synthetic is also a wise move (IMHO) - especially if you are towing. The Allison requires DEXRON-III and popular synthetic choices include Transynd (made by Castrol specifically for Allison), Amsoil Synthetic ATF and Mobil-1 ATF. I did a complete flush and refill on mine with Mobil-1 ATF mainly because it was readily available from Autozone at $5/qt.

If you do a search on "Allison fluid change" in the 2500HD/3500 Accessories forum you'll find much more info like the following:

allison deep pan and transynd change-over (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=7;t=005080)

Allison fluid/filter change HELP (http://forum.thedieselpage.com/cgi-bin/ultimatebb.cgi?ubb=get_topic;f=7;t=003150)

smile.gif

On Edit,

Dittos to John's comments above (appears we were posting a the same time)

[Lonewolf867]

A question about the actual change out. I am NOT going witha deep pan at this time...(I know it is better). But I want to get the tranny fluid changed out pretty soon.
How much fluid is needed for the actual flush fill?
I see guys buying 5 gallon cans. Does it really take it all?
Mike

[jbplock]

Mike,
I checked my notes and when I flushed mine I used 13.4 quarts with the OEM pan. smile.gif

[Russ Denman]

Do not use the AMSOIL ATF, they have formulated a new automatic transmission fluid called Torque-Drive

[Mudflap]

The basic fluid change just using the drain and spin on filter is 8.4.quarts. I used Allison Transynd ($29.00 gallon at Allison) at 44,000 and again at 80,000 miles, with a filter change at 60,000. They guys at Allison tell me this is OK. The fluid was as pink coming out as when I put it in. I used to pull a travel trailer at 11,000 lbs, now I pull a fiver at 14,000. You can break the lines and flush the system but it is not necessary according to Allison. (Wiiliams Detroit-Diesel Allison, Hubbard, Ohio)