Transmission Fluid Change 2013 Chevy Duramax Allison

A. You’re dealer is stupid. What they said makes no sense and the price is cheaper than it should be, especially from a dealer, beware
B. Agree on the no power flush. Is that actually still a thing?
C. Have all the fluid replaced with Transynd or equivalent. Change spin on filter ( you should have a couple times by now anyway...right) Any place that knows what they’re doing will pump out the old fluid ( by way of disconnecting a cooler line) and replace fluid. That’s how it should be done.

I agree with what ktmrfs wrote.

Allison Transmission
Look and see if you have a local Allison dealer. I have one local and their filters have been much cheaper than anywhere else.

internal filter does not need to be replaced. Allison/GM say only to change the internal filter if work is done on the transmission. Since the pan has a drain plug, no reason to drop the pan.

Next on fluid, If you use Dexron XXX then fluid change is at around 50K miles. And GM fills the transmission with Dexron. Now if you want extended drain intervals, (100K+) and better protection have it filled with Allison Transynd. After one fill you will need to change it again at 50K, then go to the extended fill. Transynd is expensive but I found that here NAPA stores have a castrol branded transynd at a reasonablle price.

Allison recomends against a flush, So if you want go buy a Allison spin on filter and fluid and to the change yourself. Just drain, replace what you drained, check level cold to be in the lower hash marks, then go for a drive to get the fluid up to about 180F and check again and top off if needed.

You can go to the Duramax forums & pose the question or search the forums for answers....

Allison is (I think) the only tranny in it's class with a spin on filter. So it gets replaced, but the internal one doesn't.

But I didn't think it needed to be done at 50K. Where are you seeing that?

Edit: Ahh. They changed fluid at some point to one with less life. So 50K if using GM fluid. External filer at the same time and don't touch the internal, unless doing a full overhaul.

http://fccc247.com/3%20Chassis%20Vendor%20Information/Allison%20Transmission/Allison%20Transmission%20Fluid%20and%20Filter%20Change%20Recommendations.pdf