I know it’s become somewhat customary for us to change our transmission filters more often than the manual says.

I know people have been changing them at home without running the automated hydraulic flush that is required before they change the filter at the dealer.

I found a way that you can do the automated flush before you change your filter at home, so I made a video about it:


Hope it helps.

 

Thanks for taking the time and showing us this nice video!

 

Nice vid well done, informative ...appreciate the effort. Does the forward panel have to be fully removed, or can one remove the rearward bolts and slide the alloy plate a bit rearward to drop it?

 

I'd like to do the DCT flush in my 2020 but my understanding is only the later cars (2023 and beyond?) can be done with aftermarket scan tools. However the earlier cars need to use the GM MDI tool and software. Do you know if the tool you used can be used on a 2020?

 

I had the same question and one observation. Since this is a Z06 its a 2024 (maybe a 2025 but probably not). So yeah - the aftermarket scan tools works on the later model cars, but the 2020, 2021 and not sure of 2022 do not have the built in software to executed the HSF. So the GM tool will load the softeware (each time is my understanding) before executing the HSF. And so far, its been reported on the forum that the aftermarket tools will not execute the HSF on the earlier model cars.

Second thing - aren't his comments about the track fill incorrect? He said he cant do the fluid level check because its a Z06 and has the track fill. But all Z06 have the new case and do not require a track fill - they are filled to the level of the side plug. Right???

He also did not talk about the Hydraulic System Leak test - which is or was part of the procedure in version posted on the forum. Is that still a step in the filter replacement.

Other than that, I liked the video a lot - it was a nice clear presentation of the change, and one could hear the rpm increase noticeably during the HSF, which took 8 minutes.

 

Great video! I have no intention of doing it myself but it's nice to see what's involved first hand. Thanks

 

Question- is the same flush procedure used for both the 7,500 mile filter change and the 3 year/40,000 mile oil and filter replacement?

 

Per the service manual the hydraulic system flush is to be performed prior to every DCT filter replacement. The DCT filter replacement occurs at 7,500 miles, 22,500 miles, and every 22,500 miles thereafter. There no time requirement for the replacement for the DCT filter but the DCT fluid must be replaced every 45,000 miles or 3 years, whichever comes first. There is no requirement to do the filter change and fluid change at the same time.

 

The hydraulic system flush procedure is step 1 of the procedure to change the DCT external canister filter. There is no indication in the procedure that says the HSF is only performed for the first filter change - it is the same for every filter change.

There is no "3 year/40000 miles oil and filter replacement" in the maintenance schedule.

The DCT filter is changed between 7000-8000 miles even if done earlier, then at 22,500 miles, then every 22,500 miles after that, or every 24 hours of track use, whichever is first. There is no 3 year requirement for the filter change.

The fluid is to be changed when the fluid life monitor says so, or 45000 miles (not 40000), or at least every three years (and the fluid life monitor does not include time so the owner must observe that), or every 24 hours of track use, whichever is first. It is a simple drain and fill - there is no hydraulic system flush included in the fluid replacement procedure.

The fluid and filter are on separate schedules and typically not replaced at the same time.

 

Thanks I just assumed that an oil replacement would include a filter change.

 

I have heard people say that just removing the plate is possible by the method you describe. The GM repair manual says to do both so that is what I showed, but I believe you are correct and it does save quite a bit of time.

 

I do not know the answer. If someone in Kansas has a 2020 and wants to meet up, we can find out. It is my understanding that the only reason this scan tool can do what it does is because of New Jersey right to repair laws that require the consumer to be allowed to do any programming that a dealer can do. I would have thought it would work on a 2020, but perhaps that is not the case?

 

Great questions.

I talked to the engineer in charge of the transmission at the Bash in 2022. The way he presented it to me was that the case (all cases) have plenty of room for extra fluid and that the Z06 comes with two extra quarts from the factory. I can tell you that I pulled the fill bolt on this Z06 very briefly and carefully to see if I would be able to add fluid and fluid came rushing out at me. In the manual, it shows to fill it to the fill plug and then add two quarts via the plug on the top of the transmission under the air box.

I believe there is a leak test required in the manual. I was 100% sure there was no leak and did not perform the test. Probably a missed opportunity, sorry about that.

 

Nice video - thanks for posting it here on the forum.

 

Well, I don't have a later version of the service manual so mine does not cover the Z06. In my manual there are separate sections for the normal drain and fill and the track fill. Only the track fill requires filling from the top, behind the airbox.

Here is what Josh Holder, C8 Chief Engineer, said about the Z06 and the new case. Sure does sound like the cars with the new case, including the Z06, do not have 2 extra liters, do not need 2 extra liters for tracking, and Josh does not advise doing a track fill.

"Conti: Are the two additional quarts already there?Josh Holder: It’s not really the case (meaning no). The case is, literally, changed for ’24. We did it because the Z06 necessitated a change in the lube system. Where we keep all the critical oil in a car on a Z06 that has so much lateral capability, was super important. So knowing that we needed to change the case and update the lube system for the Z06, in 24 model year, actually very late in 23 as it turns out, we moved all Corvettes to the same differential, er, the same transmission housing that the Z06 has. And when we did that you no longer need to add the additional 2 liters of oil. That (referring to the overfill) really was a way to keep (the) lube system healthy, lubrication where it needed to be, but it was overkill, it wasn’t kind of the way we would have done it starting over.

Conti: Is the pick up point different – is that what it is?

Josh Holder: The pick up point is not really different. What is different besides the the size and shape of the case itself, which can hold more oil near the pick up point, but there’s baffles inside the transmission that under high G loading keep the oil near the pick up point, which is the whole goal of (the) lube system. So that’s the benefit that all Corvette receive in 2024 models."

Conti: what if a guy (sic) did put the two additional quarts (sic) in there?

Josh Holder: In the 2024 transmission? Conti: yes. Josh: I…You could do it, actually you might risk some expulsion through the vent tube. It would be a wasted effort. So, I would not recommend doing it in a 2024. And honestly, when we recommended it in 2020 it was for a really extreme scenario, and in hindsight, I’m not sure we would’ve made the same recommendation. Its not easy to do for those that have done it themselves, a I’ve done it myself. Its not super easy. And so, we’re really glad that we got to take that revised lube system strategy to all Corvettes. And now anybody that wants to tracks their car or don’t track their car doesn’t have to worry about whether they have to add two liters or not and am I going to be that person that drives so extreme, maybe I need two liters, maybe I don’t. Takes that question out of it."

 

Good video

 

This really prompts more questions. Since the Z06 does not/ never did have the overfill requirement/ recommendation, why did yours have it and who put it in? I assume yours was used and a previous owner?

 

Excellent Video ! Best one I've seen........... SURE WISH these tools would work for a 2020 for the flush procedure. If anyone can verify, yea or nay it sure would be appreciated.

 

Great video, thanks for taking the time to make and post.

 

Like the Hydraulic System Flush, the Hydraulic System Leak test is computer initiated. I do not believe it is checking for external leaks - I think its testing for internal leaks. The instructions I have seen do not include in visual inspection for leaks - it just says to start the process with the scan tool - then follow the instructions on the screen. See if your scan tool has the leak test. I think I just saw another post showing the leak test option on a tool -but it may have been the GM tool.