- Thread starter
- #21
I believe that's done when they change the inner filter, just above the pan. Not for the outer.
C8 transmission filter service
- Thread starter Hanko_
- Start date
No, it is for the canister.
- Thread starter
- #23
? I've watched several YouTube clips of guys doing the outer filter, didn't see or hear of a flush.
Because they are doing it themselves.
Although It's Conti, his technician is good. Watch here at the 2 minute mark
- Thread starter
- #25
This is getting confusing. What exactly is a "Reverse flush"? I'm aware that you should run the engine and shift between F and R for a few minutes to warm the fluid, and run it through the filter just before changing the filter. Same thing?
The clip also alludes to losing "4 to 6 oz" of fluid when you remove the filter. Yet the dealer charged $58 for a full liter to top it off.
The clip also alludes to losing "4 to 6 oz" of fluid when you remove the filter. Yet the dealer charged $58 for a full liter to top it off.
The "flush" is a procedure that runs all the fluid through the filter. I don't think that happens necessarily in normal driving. I've had it explained to me but it wasn't retainable by my brain. lol. Yes, the dealerships charge for a whole quart, but never use all of the quart. Just another dirty little thing dealerships do.
From what I have discovered apparently just driving it for 50 k or so just before you pull in for service is just as good as a flush . Forces the oil through the filters just as well as the " flush " . Search it on Perplexity ! And yes , the TX fluid is $$$ but , not as expensive as a new TX which is I believe manufactured in Canada so they get the big tariff . Swine .
Not according to GM. Just saying.
I will try and find the source when I sober up....
GM wants you to do this with no fluid exchanged: GM GS2 (The Global Diagnostic System 2) service tool with MDI (Multiple Diagnostic Interface) commanding the transmission to run all the fluid through the DCT filter before they change it. This is called a flush procedure by GM. In Neutral the car is run at 2000 rpm for 5-10 minutes, then back to park at idle is what the GM technician is told to do. The DCT filter can now be changed. It holds 4-6 oz of fluid. The 2020-2023 Z51 cars can be topped up with the 2 extra litres at this time. If you do this tell your service advisor so the technician doesn’t pull the plug to check it at future servicing or the 2 litres will be lost. The transmission fluid is required to be changed by GM every 3 years. For most, the time element will come up before the milage on the car reaches 72,000 km. This requirement to preserve your drivetrain warranty is not just for the first 3 years it is required every 3 years. Covered by GM maintenance plans if you have one, requires 11-12 litres to complete, but the fluid will not fully drain and requires only 8-9 litres to fill the transmission back up. These services do not come cheap. A DCT filter change exceeds $850 and a fluid change is over $1000. Based on the model year of your car excluding 2020 models, you have two years to get your first free DCT filter change and three years for 2024-2025 models when you milage reaches 12,000 km. Brake fluid is also supposed to be changed every two years. I have arranged for CCF members employee pricing if anyone is interested in a GMPP Maintenance Plan. It includes all of the services mentioned above plus oil & filter changes, all air filters, coolant changes, brake pads, shocks and more.
For those that like to service their own cars here are some cost savings tips : If you need to change both the DCT filter and also need to change the transmission fluid they can easily be done at the same time. The TWO Skid plates under the C8 need to be removed for either service saving labour time for removing and reinstalling them twice and the time is significant because there are 41 bolts holding them on. Dealers charge 3.5 hours to do the DCT filter change alone to remove these trays and complete the job. You can buy the genuine GM canister DCT filter kit #24045729 from GM Parts Depot www.tubmangmpartsdepot.cafor $162.44. (dealers charge $287.11 for the same filter) You can buy the genuine FFL-4 GM transmission fluid #19418016 for a reduced price of $39.49 and if you [email protected] and mention me or that you are a CCF member you will receive and additional 10% off the fluid plus free shipping by using the code ShipGMPD at checkout. (that’s $35.54 for a bottle when dealers charge up to $61/litre). You can also check with your dealer for a quote on these parts. There has been a recent price increase in these parts so check with Chris at GMPD for updated pricing. In summary, by doing the work yourself you will save more that $1,500.00. You can do the flush procedure as described above and report to your service advisor that the DCT filter and/or transmission fluid changes have been done with your parts receipts acting as proof to be logged into the GM computer with your current milage at your servicing dealership. As we are now in the sixth production year of the C8 and GM has already denied powertrain warranty claims on cars where owners have refused to service their vehicles as covered in the owner’s manual under “Required Services”. If any of you have any questions, feel free to reach out. This is a $21,000 part and 1.5 days labour to replace it. I encourage each of you to pay close attention to the maintenance requirements of your TRANSMISSIONS!!
For those that like to service their own cars here are some cost savings tips : If you need to change both the DCT filter and also need to change the transmission fluid they can easily be done at the same time. The TWO Skid plates under the C8 need to be removed for either service saving labour time for removing and reinstalling them twice and the time is significant because there are 41 bolts holding them on. Dealers charge 3.5 hours to do the DCT filter change alone to remove these trays and complete the job. You can buy the genuine GM canister DCT filter kit #24045729 from GM Parts Depot www.tubmangmpartsdepot.cafor $162.44. (dealers charge $287.11 for the same filter) You can buy the genuine FFL-4 GM transmission fluid #19418016 for a reduced price of $39.49 and if you [email protected] and mention me or that you are a CCF member you will receive and additional 10% off the fluid plus free shipping by using the code ShipGMPD at checkout. (that’s $35.54 for a bottle when dealers charge up to $61/litre). You can also check with your dealer for a quote on these parts. There has been a recent price increase in these parts so check with Chris at GMPD for updated pricing. In summary, by doing the work yourself you will save more that $1,500.00. You can do the flush procedure as described above and report to your service advisor that the DCT filter and/or transmission fluid changes have been done with your parts receipts acting as proof to be logged into the GM computer with your current milage at your servicing dealership. As we are now in the sixth production year of the C8 and GM has already denied powertrain warranty claims on cars where owners have refused to service their vehicles as covered in the owner’s manual under “Required Services”. If any of you have any questions, feel free to reach out. This is a $21,000 part and 1.5 days labour to replace it. I encourage each of you to pay close attention to the maintenance requirements of your TRANSMISSIONS!!
Maintenance Plan brochure
Excellent info . Is the brake fluid change at two years a warranty issue and , yes I know I should look it up , but is it included in warranty service under both plans ? Thanks yet again .
I have written to GM for confirmation but as it was explained to me the brake fluid change at 2 years is not covered by the base 36 months bumper to bumper warranty but is covered by the maintenance plan that I posted the brochure for tonight.
I now have confirmation from GM that what I said initially is correct. Not covered by warranty but is by maintenance plan.
DenisC8
Power User
So 2024s have 3 years instead of 2 to get free dct filter change? Was there a letter about this?
No letter, we just learned it after the 2024's came out.
It's not a flush in the traditional sense of the word (fluid exchange). It's a computer controlled process called the "Hydraulic System Flush" that cycles fluid through all the valves in the DCT and through the filter to get as many particulates trapped in the filter as possible before the external filter is changed. It requires either the GM software on a laptop, or a specific aftermarket tool that's capable of doing the process. In the GM online service manual, it's step one of the DCT external filter replacement procedure.
There's nothing in the GM service procedure called a "reverse flush." Just the HSF described above. And yes, your dealer ripped you off.
This a lot of confusion about this, largely created by Josh Holder, Corvette Chief Engineer. At the Bash in 2024, Holder said that while driving on the highway they've programmed the TCM to do essentially the same thing as the HSF. But not exactly the same thing, because cycling the valves would, I believe, cause the DCT to shift gears. He said that if you're a DIYer, you can change the filter without doing the HSF. Harlan Charles and Tadge Jeuchter were with him, and neither disagreed.
BUT, the service manual specifies the HSF as step 1 of the external filter replacement. It doesn't say "unless you don't have access to the software," or "unless you're a do it yourselfer." If you have a DCT issue under warranty, and didn't do the HSF, it won't be Josh Holder who decides if it's covered by the warranty.
At the same time, it appears not all dealers follow the procedure and perform the HSF. So, is it OK to skip the HSF? Your call.
Does GM really say the brake fluid needs to be replaced every 2 years in Canada? My US 2021 owner's manual says every 5 years.
The 2024 US Owner's Manual says the same thing.