I have owned four C8s (a Stingray, two Z06s and the ZR1 I have now) and daily driven them for years. The DCT filter is a small job with a big warranty attached, because GM reviews maintenance records on transmission claims. Here is what GM requires, what it costs, how hard each job is, and what the warranty does when the DCT acts up.

What GM’s maintenance schedule requires, and when

The C8’s 8-speed dual-clutch is built by Tremec, and GM’s service articles call it the TR-9080. It has an external canister filter that GM treats as scheduled maintenance. GM’s TechLink article for dealer technicians sets the first filter change at 7,500 miles (12,000 km) and every 22,500 miles (36,000 km) after that. The letter GM mailed to owners, published by CorvetteBlogger in November 2024, names the odometer points: 7,500 miles, then 22,500 miles, then every 22,500 miles. That puts the filter services at 7,500, 22,500, 45,000 and 67,500 miles.

The fluid runs on a clock. The owner’s manual text GM quotes in that article says the transmission fluid must be changed at least every three years. If the car shows CHANGE TRANSMISSION FLUID SOON, you have the next 1,000 km (about 620 miles) to change both fluid and filter. If fluid life reads below 10 percent, replace both.

The details that catch people out:

• Why 7,500 miles. GM says break-in wear creates the most contaminants, and its warranty bulletin states the transmission is not fully broken in until 7,500 miles.
• Early does not count. A filter replaced more than 500 miles before 7,500 has to be replaced again within 500 miles of 7,500, and GM does not pay for the early one.
• The window. GM engineering says plus or minus 1,000 miles should not hurt anything. The free service is claimable from 7,000 miles, or once the cluster shows Replace Transmission Filter Soon.
• The reminder. Starting with the 2023 model year, the cluster shows a message shortly before 7,500 miles and every 22,500 miles after. GM notes it cannot be reset the way the oil life monitor can.
• Low-mile cars. On 2024 to 2026 cars the free filter is good for three years from purchase. Under 7,000 miles at that point, it becomes your cost.
• Overdue cars. GM tells dealers to replace the filter, run the hydraulic system flush, then fit a second filter. Flushing first would push debris back through the system.

Which model years and models this covers

GM’s article names 2020 to 2024 Corvettes under transmission codes M1L and M1M. M1L is the code GM pairs with the Z51 package, so that is the Stingray unit. A third code, MLH, appears in GM’s 2025 repair article covering 2020 to 2025 cars. The warranty side is GM bulletin 24-NA-081, which covers the 2024 and 2025 Corvette as a model line and carves out no variant. CorvetteBlogger reported in November 2025 that 2025 and 2026 buyers sign a form at delivery confirming the same window: 7,000 to 8,000 miles, inside three years.

I could not find a GM document that sets a different interval for the Z06, E-Ray, ZR1 or ZR1X, or one that changes the numbers for 2027 cars. The schedule in the owner’s manual for your model year is what GM will hold you to. One procedure change is on record: for 2026 and newer cars, GM told dealers they can skip the hydraulic flush during the filter change, per CorvetteBlogger’s March 2026 report. The flush is still part of the fluid change.

Parts: the filter, the fluid and how much it holds

GM specifies DCTF FFL-4 C8 Corvette transmission fluid. It is sold in 1-liter (1.06-quart) bottles under GM part number 19418016. GM tells technicians to shake the bottle hard before pouring, and a sealed bottle has a three-year shelf life. The filter comes as a canister filter kit. A GM parts vendor on Canadian Corvette Forums quoted it as part number 24045729 in May 2025. Part numbers get superseded, so confirm it against your VIN.

Capacity is where the two jobs split. One Corvette parts vendor lists the transmission’s approximate overhaul capacity at 11.62 quarts, about 11 liters. The canister filter holds 4 to 6 ounces, according to the forum vendor, and GM allows the dealer one quart for top-off during a filter service.

What dealers charge versus DIY parts cost

GM publishes no retail price for either service. The dealer numbers below are owner-reported quotes from the threads that rank at the top of Google for these searches, so read them as a range. Parts prices are as listed in October 2026.

GM reimburses a U.S. dealer $250 for the covered filter service, while owners have posted retail quotes of $800 for the filter and more than $1,300 for fluid and filter. In parts, the filter kit is $195 to $199.99 and the fluid is $42.00 to $46.18 a liter. A DIY filter change is one kit plus a liter for top-off, about $240. A full fluid change at $42.00 a liter is $462 in fluid if you buy all 11 liters. The gap is labor: the forum vendor says dealers book 3.5 hours for the filter alone.

The DCT filter change in outline

This is an outline so you can judge the job, not a replacement for GM service information. I am not printing torque values I cannot source.

1. Get the car in the air. You need a lift or tall, stable stands.
2. Remove the underbody panels. Two panels held by 41 bolts, per the forum vendor.
3. Swap the external canister filter. Expect to lose 4 to 6 ounces of fluid.
4. Top off and check the level at the inspection plug, with FFL-4 from a shaken bottle.
5. Flush, depending on model year. Through 2025 the dealer procedure included a hydraulic system flush run with a scan tool. On 2026 and newer cars GM lets dealers skip it.
6. Keep the filter receipt with the mileage and date. GM’s article tells owners who do their own service to do exactly that.

Why the fluid change is the harder job

• Volume. About 11 liters of capacity against a few ounces for the filter. The forum vendor notes the transmission does not drain completely, so the final level check matters.
• The flush. The hydraulic system flush is still part of the fluid change. It runs through GM’s dealer scan tool (GDS2 with the MDI interface) or an aftermarket tool that can command it.
• The reset. The owner’s manual requires the Fluid Life System to be reset afterward.
• The fill points. There is a side fill plug and a top plug under the airbox. The side plug is easier to reach.

Video: Paragon Performance changes a C8 DCT filter step by step

Paragon Performance walks through the canister filter change start to finish, including the tools you need. The video has been on this site since June 2021, so the car is an early Stingray and it predates the flush guidance above. The mileage points in its description match GM’s schedule.

Track use: the extra two liters

GM has a separate rule for track days. A Stingray with the M1L transmission and Z51 gets two additional liters of fluid before track use. Transmissions coded M1M or MLH need no track fill, and neither does any car with what GM calls a Die 3 case, which bulletin 23-NA-156 identifies. The side-plug method is in how to add the extra DCT fluid, and the rest of the checklist is in how to prepare a C8 for the track.

Will GM replace your C8 transmission? What the warranty covers

The DCT falls under Chevrolet’s Powertrain Limited Warranty, which Chevrolet lists as typically 5 years or 60,000 miles, whichever comes first. Bumper-to-Bumper coverage is 3 years or 36,000 miles. Per Chevrolet’s warranty page, transmission coverage includes the case, internally lubricated parts, seals, gaskets and internal electrical components.

Coverage is tied to maintenance. GM says missing canister filter service may affect coverage, and a previous owner’s missed service can count against you, so ask for filter records before you buy a used C8. The exception GM names is case porosity, which is not affected by missed maintenance.

Repair or replace depends on the fault. Until September 2025, a park lock valve fault meant a complete transmission. GM has since released parts and a service procedure for the valve and harness on 2020 to 2025 Corvettes. CorvetteBlogger puts a replacement transmission at $20,000 or more. The owner cases this site followed in 2021 and 2022 ended three ways: a control module reset and relearn, a valve body, or a new transmission under warranty.

Known C8 DCT issues GM has documented

Everything in that table is a service bulletin or a GM technician article, not a safety recall. A bulletin is applied when a car shows the symptom. To see recalls open on your car, run the VIN at nhtsa.gov/recalls. The wider list is in my C8 Corvette problems guide.

Warning signs, and what to do when the DCT throws a fault

• A message telling you to put the car in park and take it in for service.
• Fluid leaking from the transmission.
• A hard jerk on the shift from first to second, or a car that will not shift.
• A check engine light with new noises from the transmission.

Replace Transmission Filter Soon and CHANGE TRANSMISSION FLUID SOON are maintenance reminders, not faults. For a real fault, this is the order I would work in:

1. Photograph the message and write down the mileage.
2. Do not throw a filter at it. GM says a filter change will not repair a transmission that is already showing symptoms or setting codes.
3. Get it to a Chevrolet dealer with your filter and fluid records. Inside 5 years or 60,000 miles it is a powertrain warranty claim.
4. Ask whether the fault matches 23-NA-176, 23-NA-197 or the park lock valve repair.
5. If it has to go on a flatbed, see how to get a C8 into neutral with the engine off.
6. If the transmission is replaced, the next filter is due 7,500 miles after the install, and GM says to drive it like a new car for the first 1,500 miles (2,400 km).

Not every driveline failure is the gearbox. I broke a rear half shaft launching my Stingray, which is an axle problem, not a DCT problem.

Frequently asked questions