HD Pickup Transmission Question

My older 2500 HD has passed the 100K mark and want to service tansmition.
Is it better to Flush it and change filters and fluid or skip the flushing and just
change filter and fluid?
A GMC dealer wkill be prefomring this.
Thanks

Skip the flush and do a filter and fluid replacement…..but do this more often, around every 30-40k. Friend of mine did this on a fleet of GM service trucks and they all made it over 250k without issues.

Do both, they only get about half to two thirds the fluid capacity out when dropping the filter. And sorry to do this but it is “Transmission”

I would only change the filter after that amount of mileage. Even replacing the fluid would probably cause slipping.

If it is an allison, do a flush as well. If not just change the filter and top off the fluid.

Thanks everyone and I can’t beleive I posted this in classifieds!!!

Mike West wrote:

Thanks everyone and I can’t beleive I posted this in classifieds!!!

Fixed that for you.

-J.

I would flush it. Why just drop the pan and add 5 quarts of fluid to the 3 or so dirty quarts still left in the converter and stuff. Flush uses 15 quarts to replace your 7 or 8 old quarts.

Thank you Sir!!!

I have always been of the belief that draining and replacing the filter is better than “flushing” it. When its flushed its pushing whatever back through the system and you’re not replacing the filter. There are ways to get a complete drain when dropping the pan, my local shop does it for me when I have it done, but I get rid of my vehicles typically before its required. The last two years I havent put on hardly any miles since I am working remote. I used to put on 25,000 per year and trade every 18 months. I have had this truck for 3 years and only have 41,000 miles on it.