2007 denali 145K...trans flush or no?

[11bravo]

My Denali trans is okay, sometimes a very slight quick-shift form 2-3 on a light throttle, but most always just smooth shifts up and down. Fluid is still pink, but with a slight tan to it. I was considering a trans flush versus just doing my own fluid change, but a shop I called recommended against the flush due to miles on the trans. Do any of you have hard evidence against the flush with my mileage?

If I do it myself, I will do two changes a couple hundred miles apart, and change the filter on the second change. Cost is not an issue for flush versus doing the change myself..

Thoughts?

 

[Foggy]

Don't "flush". Just service it normally. Filter, Clean pan, new fluid.
If it makes you feel better, just do it again in a couple of months or so...
Always drop the pan. Clean up everything. New Filter & Fluid...
Just changing the fluid only does very little

 

[petethepug]

No flushy. The slip is the warning sign on 07-08 trans. You wouldn’t want to dislodge anything into the system at that milage.

For giggles and kicks shop around for a 2019+ 10L80 10speed trans. If you source one from a running known good / crashed truck, plop that in and begin the ear to ear grin.

Home - Powertrain Swap Solutions

www.powertrainswapsolutions.com

https://static.nhtsa.gov/odi/tsbs/2014/SB-10043845-3346.pdf

 

[donjetman]

Change it.
When we bought our 07 Denali in 2018 it had been road had for 130k miles. Fluid looked bad.

I pulled the tranny out to do a rear main seal job. While tranny was out I changed all 12 qts of atf because I change the torque converter too.

Today at 200k miles it working good still

 

[Marky Dissod]

Don't "flush", just service it normally. Filter, clean pan, new fluid.
If it makes you feel better, just do it again in a couple of months or so ...
Always drop the pan. Clean up everything. New Filter & Fluid ...
Just changing the fluid only does very little.

I THINK a different version of what he's trying to say, is to
drop the pan and change the filter more often
more often than the manual says under 'severe service'.

 

[petethepug]

No on the flushy, yes on a typical fluid & filter change as Foggy said.

Your 6L80 exhibits the symptoms of cracks in the shift housing as well as the shift flare.

Be mindful of investing in labor, parts and fluid you’re going to be due for shortly (again). The trans is already at the tail end of its service life.

When the 6L80 in our 08 had the same symptoms I bought an 09 to get e85, no peel pearl paint, no crack leather dash and a/c seats. The Esky was $2.5k more than what the YXL Denali sold for with the same 140k milage.

You’re choices are:

* Do nothing
* Prep for it by getting bids.
* Prep more buying new OEM motor mounts, front diff, ARP exh mani bolts.
* Buy, sell or trade for another w/o AFM (07/08/09).

Going from an 08 to an 09 prolonged my trans replacement for another 3 years. This was back in 2020. Your milage is low buddy.

 

[donjetman]

@11bravo
Here is a discussion with used atf analysis reports:
https://www.tahoeyukonforum.com/threads/atf-lab-results-dexron-vi-43k-miles-on-fluid.134360/