drain plug torque spec, as per post. Install and tighten 25 N-m  (18 lb ft) ???

 

I used the specified torque and it didn't seem excessive but I don't remember the plug being aluminum. I have a 2020 with the die 1 pan, perhaps the later pans are different and the service manual has a different torque for the plugs in the cast aluminum pan?

 

Ok, as long as you keep the bolts with the right cover, you can't mess it up.

 

Can you perform a filter only change on the transmission, and do you have to add some amount of fluid for the loss?

Is there a filter only change set of instructions somewhere?

 

Yes. The DCT filter replacement and the transmission fluid replacement are on two entirely separate schedules. And yes they have separate procedures - always. And yes, when the filter is replace there is a small amount of fluid lost - and are steps in the procedure to check and adjust fluid level.

The procedures are in the Service Manual for each.

The DCT filter must be changed between 7000-8000 miles even if done earlier, then at 22,500 miles, then every 22,500 miles after, or when the filter life monitor says so (if you have one), or every 24 hours of track use, whichever comes first.

The fluid must be replaced when the fluid life monitor says so, or every 45000 miles, or at least every three years,or every 24 hours of track use, whichever comes first.

So, you can see they will generally not happen at the same time - many will get to 3 years before reaching 45000 miles.

 

What would be swell is to find software / hardware that is useful on a 2020 Corvette C8 for the required Hydraulic System Flush. There's currently available software / hardware for newer model years but nothing for the 2020... yet.
### UPDATE: I've answered my own question...
The Foxwell NT710 Bi-directional Scan Tool (with software for GM) will perform the Hydraulic System Flush procedure on a 2020 C8 but unfortunately it won't perform the "Leak Test" ...

 

Or, don't worry about since the "flush" occurs as you drive.

 

t not at all clear to me that Josh said that the highway routine is "exactly the same" as the Hydraulic System Flush. Below is his statement. Its ambiguous in my opinion. He says when you are driving steady state down the highway we run a routine in the transmission that will force more fluid through the fine filter. He could have said when running in steady state down the highway we run the Hydraulic System Flush procedure. But he does not say that. He does not say that "routine" is the Hydraulic System Flush. As I have pointed out before, many believe that the HSF executes the seven different Transmission Services Cleaning Procedures in certain order. There is no direct proof of that, other than those 7 procedure reportedly disappeared when the HSF appeared as an option on the scan tools. But if is true, then its hard to believe that the highway routine is doing "exactly" the same thing. Each of those individual procedures was to address an issue with one, two, or three specific hydraulic control system valves. It would seem difficult to exercise those valves that way when cruising down the highway, since they control everything from fork movement, clutch action, park lock, and eDiff if you have it. But again, I agree its ambiguous, so I can understand where others want to interpret it differently. He also said you do not have to do it if your are doing it yourself - and that part was not ambiguous.

Here is Josh's statement - and I attached the list of 7 procedures again"

"The hydraulic system flush does kind’a the way its described. It forces transmission fluid through the fine filter that you replace. So, at a dealership they can hook up the dealer service tool to the and run a routine that will tell the trans control module to do this fluid filter flush. And because the car is already hoisted on the rack, the technician’s already got the panels off, there’s some other work he’s doing, this kinda happens in parallel in the background. So we’re doing it at a dealer visit because we can. And we can take the last bit whatever contamination might be in the oil and get it into the filter before the technician replaces it. Do it yourselfers have become nervous that hey now I can’t do it myself, I don’t have a service tool, I can’t force this routine. You don’t have to do the routine. Like I said we do it because we can, but the fine filtering routine happens during normal driving anyway. In fact, when you’re driving steady state like say down the highway, we run a routine [ my note - does "a routine" mean "the HSF routine" or something else? He could have said we run the HSF when cruising down the highway, but he did not say that. Why?] in the transmission that will force more of that fluid through the fine filter. So normal driving is doing this. If you are a do-it-yourselfer, you don’t want anyone else touching your car, you can change the trans filter without running this routine."

 

if you go to you tube there’s a few good videos showing step by step instructions to perform the back flush for the filter removal.
purchase from Amazon the Foxwell NT510 elite OBD2 hand held scanner for around $189. I backflushed mine with it and it’s easy to use and works great for the flush and has a boat load of other uses.

 

What year is your car? I know some aftermarket scanners will perform a HSF on later cars but the software isn't built in for the earlier cars. I've seen one post reporting that the Foxwell worked on a 2020 but the leak test didn't work. I have a 2020.

 

Again, no such procedure called back flush for the C8 transmission - which sound like some sort of reverse flush that you might to with an exeternal device. The procedure performed as step one of the filter change procedure is called the Hydraulic System Flush. Its described like this in the Service Manual: "This test executes a procedure in the TCM software to actuate the solenoids in a specific manner to flush debris from the system."

 

in the service manual I’m not sure what it’s called as I stated I just seen it when the tech showed me what it’s doing. You are correct it opens the solenoids to clear any debris so it gets caught in the filter. The tech stated they started doing this procedure after the many DCT failures they were experiencing.
its not recommended obviously in our owners manual.

 

Good thread, worth reading all responses

 

Related question for the experts if you don't mind:

We have a '20 with just over 5K miles and I'm thinking it may be time to change the DCT fluid.

 

every 3 years or 45k miles.

 

to maintain your warranty, you are required to change the DCT fluid every 36 months, regardless of mileage.

 

100% Correct 3 years no matter mileage unless your over the 36k mileage requirement.

 

45k miles not 36k miles.

 

The statement I made was in regards to the Manufacturer’s Warranty which is 3 years or 36 thousand miles not the DCT fluid change specifications of 3 years or 45 thousand miles.
One is required maintenance schedules, and the other I was referring to was the Manufacturer Warranty which covers the warrantable components nothing to do with the required maintenance requirements.
if you still not in agreement with these statements refer to your owners manual.
regards,

 

But the DCT isn't subject to the 36K B2B warranty, is it? I thought it is covered by the drive train warranty. If so, your 36K is STILL incorrect.