Re: Duramax Allison issue
 

Switching to the Transynd fluid or as I did Delvac approved fluid the transmission is smoother. If you tow heavy you might consider using the better syn fluid.

Re: Duramax Allison issue
 

Allison was part of GM Hydramatic when the 1000 was developed . The Engineers from Indy work side by side with us in Ypsilanti . When GM went through bankruptcy Allison was spun off but the only Allison trans that remained with GM was the 1000 because it was in most of the 1-ton pickups . I think it's still built in Baltimore . Also Castrol developed the fully synthetic fluid Trans-Max , and later Allison re-named it Trans-Syn . It is a very good Automatic Transmission Fluid

Re: Duramax Allison issue
 

Would the Trans Syn fluid be better in a 2001 1000 model Allison than the Dexron?

Re: Duramax Allison issue
 

Yes! My 2003 has it. Smoother and less trans temp. Walmart is the best deal on approved Delvac Allison syn. I don’t use Castrol...

Re: Duramax Allison issue
 

Summit's price was the best I found, never checked Wallmart.
Yes trans shifts smoother & runs cooler.

Re: Duramax Allison issue
 

Works so well in the truck I’m tempted to try it in the race car.

Re: Duramax Allison issue
 

I've used Transynd in Powerglides behind some big HP in an attempt to get better pump life when the pressure gets over 225 psi and it definitely seems to help. It is a full synthetic and a higher viscosity than regular Dex 3 fluid. Castrol was the original supplier when Allison wrote the specs for the fluid, TES-295. They have since added a few suppliers to the approved list. As far as what to use in an Allison, I wouldn't use anything that they haven't approved to TES-295.

Jim Mantle V/SA 6632

Re: Duramax Allison issue
 

Allison part #. Change every other oil change. Deep pan and Transynd 30k. Transynd doubles the service life in conjunction with additional ATF (deep pan). Don't forget to take the magnet out of the old filter, to put in the new filter.

https://i.imgur.com/jKFkkcC.jpg