The 8 speed Colorado is approaching 25k miles. I want to stay on top of fluid changes in this unit being they were previously prone to shudder issues. Is a flush the right way to go? I've read that some don't recommend flushes, but that seems to be based on the mileage of the vehicle.
GM 8 speed Transmission Flush
- Thread starter buster
- Start date
When the shudder problem first arose in the early 8 speeds and GM determined a switch from Dexron VI to the Mobil 1 LV ATF (blue bottle) was the fix. The GM TSB called for a complete flush of the Dex VI replacing with the Mobil 1 LV. GM dealers had to obtain a special machine to perform the flush. Between all of the trucks and cars with the 8 speed shudder I am sure GM has performed a million flushes by now. I see no problem.
However, by the time your '22 ZR6 was made GM was using the Mobil 1 LV on the production line. It is a synthetic ATF and I highly doubt it needs replacing at 25K miles.
However, by the time your '22 ZR6 was made GM was using the Mobil 1 LV on the production line. It is a synthetic ATF and I highly doubt it needs replacing at 25K miles.
Bud_One
Site Donor 2022
Our current fleet has eight vehicles (1 2021Canyon , 2 2022 Colorados , 1 2024 Silverado , 4 2019 G-Vans ) with this 8 speed transmission.
The three older 2019 Vans have had the transmissions go out at roughly 120k-130k miles .
As a precautionary measure , we're having the newer ones we've purchased transmissions flushed every 30k miles .
I think it's a good plan considering this transmission's track record.
Just my 2 cents.
The three older 2019 Vans have had the transmissions go out at roughly 120k-130k miles .
As a precautionary measure , we're having the newer ones we've purchased transmissions flushed every 30k miles .
I think it's a good plan considering this transmission's track record.
Just my 2 cents.
That's my thought as well. Just keep it as clean as possible with periodic flushes.
I completely agree with your thought process and I have a 2019 which was subject to that TSB and the weird shudder started happening at 10k miles. My local deal did not even have the new trans machine which is a giant pump basically that hooked into under the trans and allows them to us the transmission itself as part of the way the fluid is pumped out and then refilled at the same time apparently. I uses 14 quarts of that new spec DEX VI and you its not even easy to find that stuff for sale the old version is now marketed by everyone of course. Fearing exactly the kind of thing you listed yourself I went back to them at just over 55K thinking my warranty was coming to an end so would of course the trans. Amazingly enough the service writer heard my cries and put it through the same TSB exchange which I did not pay for again and its still running like a dream 10K later. After all that if I do end up keeping it long term I will just pay them to do it again sometime just before 100K is my plan as I also did all the axles and transfer case fluild just after that 55K service last year. There seems to be zero way to do this at home properly as there isn't even a fill plug or dip stick level. Wonder if they will let me buy the fluild myself?
Did you have the 2019 done per the TSB with the trans flush of the incorrect fluid?
ATF changes keep this particular transmission shudder free.
They started putting the new Mobil 1 LV in the 2020 models. I was told there was some tweaks done to the torque converter as well for the 2021-22.
Bud_One
Site Donor 2022
Eventually we did , but it was close to 100k miles before being serviced .
Bud_One
Site Donor 2022
No dipstick , fill and dribble routine.
Bummer. Any better technique than to do it after letting the truck sit overnight so fluid is room temp, measure what comes out, and put in the same amount?
To Bud_One: You said,
"Our...eight vehicles with this 8 speed transmission.
... three {went} out at roughly 120k-130k miles .
As a precautionary measure...flush every 30k miles .
I think it's a good plan..."
What you posted is worth WAY MORE than 2 cents.
"Our...eight vehicles with this 8 speed transmission.
... three {went} out at roughly 120k-130k miles .
As a precautionary measure...flush every 30k miles .
I think it's a good plan..."
What you posted is worth WAY MORE than 2 cents.
BrendanC
$100 site donor 2024
just did a pan drop/filter change on an 8l90. got rid of the shudder felt at highway speeds. refilled with Mobil 1 HP atf.
4WD
$50 site donor 2024
Magnets loaded ?
