Jerry, can you post a link to the post about the Bash? That conflicts with what was presented at Corvettes at Carlisle in August of '21 which said to wait until 7500 miles for the DCT filter change (or change it again at 7500 miles if you change it sooner).

 

have several times. I'll look for an old post of mine. Doesn't conflict with my logic, GM's just getting around to understanding the DCT is more of an issue that the engine!

Found this with the Poster's name and my quote of his comment:
In a recent post sdcnewsstated: "I went to a maintenance seminar at the NCM Bash Guy said it was very important to change the tranny filer at the first service which is free."

Check out post # 9 this Thread:
https://www.corvetteforum.com/forums...change-c8.html

Love google, I just put in his whole quote and there is was! Actually scarry!

 

There isn't a lot of detail in that statement. If the first service isn't performed by GM until the end of the second year you are still compliant. It doesn't exclude changing the engine oil yourself earlier. And what you had GM do the first service at 500 miles?

Here is what was posted on the other forum from the August '21 Carlisle presentation:

I was at Corvettes at Carlisle today, and there were a couple of presentations by GM personnel that provided some useful information, and cleared up some confusion or misconceptions.

First was a presentation by two people introduced as the program manager for the DCT project and another identified as the Assistant Chief Engineer for the DCT. Both are GM employees, not Tremec. They emphasized the importance of doing the DCT filter change at about 7500 miles to ensure all the break-in wear products are removed. Wear products that continue through those first 7500 miles, no matter how long it takes to get there. The key point was that if you put few miles on your C8, and take advantage of the "free" filter change in the first year with only a few thousand miles on the car, you should change it again at 7500 miles to remove the wear products that accumulate after the early change.

They also emphasized the importance of adding the extra 2 quarts (yes, I know it's actually liters, but even they said quarts) if you "are tracking the car." They said in something like a fast down hill turn, the oil can actually be lifted into the top of the transaxle, causing the oil pick up to suck air. I asked them to define "tracking." Does that include a few lead / follow laps at NCM, or HPDEs, or only if you're near racing speeds?

Their answer was two-fold: First, that they think GM is changing the wording of the recommendation to "tracking or spirited driving," and second, that they would define track use as anytime the car is on a track, even lead-follow laps. I think there's been a general consensus that a few laps at far lower than racing speeds doesn't really need the extra oil. This advice seems to contradict that.

(Don't argue with me - I'm just the messenger.)

They also said a replacement DCT, out of warranty, costs $20,000!

Next was a gentleman named Paul (forgot his last name - sorry) who is the manager who deals with customers or dealers when someone is seeking an accommodation for a problem / repair that is outside the warranty. The bulk of his presentation amounted to "follow the recommended maintenance and the OLMs." He also recommended letting the dealer do the DCT filter change, because the dealer tech will (a) first do the DCT flush procedure to remove as much wear material from the oil as possible. Also, after the filter is replaced, the tech will do a pressure test to ensure there are no leaks. Neither of which can be done at home without the GM software.

I think this eliminates any question about whether the flush is part of the filter change procedure or not.

I think the message is not to skip the 7500 mile DCT filter change, not that the DCT filter should be changed at your first service if you have less than 7500 miles on the car.

 

If it was "important" to change the DCT filter at one year, when doing the required oil change at 1 year, regardless of mileage, then the Owner's Manual should say that, and owners and dealers should also be notified of the the change. As it is, the 2023 Owners Manual still says that the first DCT filter change is at 7500 miles. It does not say anything about changing it at the required 1 year oil change. I did have mine changed at 1 year and 2500 miles - and will have it changed again at 7500 miles or at three years when I change the fluid.

 

Yep that was an early GM comment about when they extended it to 24 months (after saying it was 36 months!) One reason I will have mine changed again when they change 11 quarts of DCT oil year 3 is that 7500 miles statement. That 3-year DCT fluid change requirement have been in the 2020 Owner's Manual since the early PDF, which I downloaded.

One of my key reasons for changing was the somewhat jerky motion (not that bad but noticeable) when crawling at <4 mph up to about 800 miles when I crawled into my garage. Did that with my C7's (standard shifts) and was careful with my last a Grand Sport as the rear fenders are wide and I often am not pulling in perfectly straight as I have to turn 90 degrees from the driveway and make a "K" turn to do that. Rear fender even on the C8 can get close as I control the driver's mirror tip to wood garage door molding from 1 to 2 inches so there is plenty of room on the passenger side that is harder to judge. I often stop before proceeding at a crawl.

But after that 800 to 1000 miles, it's perfectly smooth. Lots of disks on that multiplate 1st gear clutch to wear in. It's also slipping at Red lights etc, but suspect with less applied pressure. Expect most wear on gears, synchro cones, **** forks sliding on rods etc is probably over at ~1500 miles. Don't know what's magic about waiting for 7500 miles BUT since GM say I'll do it. But lots of folks tripping CEL's and dealer doing a flush per GM recommendation. Some doing it 3 times and it often solved the issue. My "guess" is GM is realizing the DCT has some initial wear issues. Expect them to still say change at 7500 miles as well. I'll have about that year 3 on my then 2-year-old filter.