2020 - 2024 Corvette: Corvette Transmission External Canister Filter and Maintenance Update, Labor Code Added

July 23, 2024

The Tremec DCT TR9080 dual clutch transmission (RPO M1L, M1M) on 2020-2024 Corvettes features an external canister filter that should be replaced at the initial 7,500-mile (12,000-km) maintenance service. After the initial service, the canister filter should be changed at 22,500 miles (36,000 km) and then at regular 22,500-mile (36,000-km) intervals. Transmission filter changes at the proper time are critical for DCT longevity.

GM has extended the factory-covered maintenance for the transmission canister filter to three years or 7,500 miles (12,000 km), whichever occurs first, on the first filter change. (Fig. 4) The three years of coverage will help cover vehicles with low miles. A labor code has been added for the filter replacement.

Fig. 4

The canister filter (Fig. 5) should be replaced in the first 7,500 miles (12,000 km) due to the initial break-in of the internal transmission components. The 7,500-mile (12,000 km) break-in period is when most contaminants may be created. Engineering recommends that the filter be changed as close to 7,500 miles (12,000 km) as possible – plus/minus 1,000 miles (1,600 km) should not be detrimental.

Fig. 5

Maintenance Coverage

It is recommended to only replace the canister filter at the required maintenance interval due to the loading characteristics of the filter. (Fig. 6) The filter does not need to be changed earlier than 7,500 miles (12,000 km).

Fig. 6

Additional filter changes can be performed, but the recommended mileage intervals should still be followed for regular maintenance. For example, if a customer elects to have the filter changed before 7,500 miles (12,000 km), it should be changed again at 7,500 miles (12,000 km). GM will only cover one filter change.

Check the maintenance schedule in the appropriate Service Information for complete maintenance information. (Fig. 7)

Fig 7.

If a transmission is replaced, it should be treated the same as the new vehicle break-in period. The canister filter maintenance should restart as if it was a new vehicle, with the next filter change at 7,500 miles (12,000 km) after transmission replacement.

New transmission replacements should follow all break-in recommendations. The vehicle should be driven like the initial new vehicle break-in period for at least 1,500 (2,400 km) to protect from damaging the differential gear surfaces.

TIP: Corvette owners should share filter change information with dealership service advisors and service management. It’s recommended that owners who do their own auxiliary filter maintenance retain the receipt for the purchased filter. GM will be reviewing maintenance records on transmission warranty claims. Lack of maintenance on the canister filter cartridge may affect warranty coverage.

Added Labor Code

A unique labor code for the external canister filter replacement is now available for factory-covered maintenance on 2024 and newer Corvettes as a standalone operation. Refer to Warranty Administration Bulletin #24-NA-081 for details regarding claim submissions for this one-time factory-covered transmission filter replacement.  The engine oil and engine oil filter continue to use the traditional factory-covered maintenance labor code.

Maintenance Minder

Beginning with the 2023 model year, the Corvette has a maintenance minder on the Driver Information Center that will display a maintenance message shortly before the 7,500-mile (12,000-km) maintenance interval. (Fig. 8) The message also will appear every 22,500 miles (36,000 km). The transmission filter minder cannot be reset like the engine oil life monitor.

Fig. 8

If the transmission is replaced, customers will need to keep track of the mileage, starting with the first 7,500-mile (12,000-km) maintenance service for the new transmission.

Transmission Fluid and Filter Information in the Owner’s Manual

In addition to the maintenance minder, customers should be reminded to follow the transmission fluid and filter change recommendations in the Corvette Owner’s Manual. The Owner’s Manual includes the following information:

• When the CHANGE TRANSMISSION FLUID SOON message displays, change the fluid and filter within the next 620 miles (1,000 km). Failure to change the transmission fluid at required intervals can lead to reduced transmission performance. The transmission fluid must be changed at least every three years, and the Fluid Life System must be reset.
• The initial transmission canister fluid change must be performed at 7,500 miles (12,000 km), and every 22,500 miles (36,000 km) thereafter.
• If the canister filter is replaced more than 500 miles (800 km) prior to the initial 7,500-mile (12,000 km) break-in period, the filter still needs to be replaced again within plus/minus 500 miles (800 km) of the 7,500-mile (12,000 km) service interval.
• The transmission maintenance schedule needs to be restarted if the transmission assembly is replaced. The new unit will require the same initial break-in maintenance.
• The transmission external canister filter must be changed at 7,500 miles (12,000 km) during the break-in period. Failure to replace the external canister filter can cause damage to the transmission and potentially void any warranty.

Transmission Fluid

The DCTF FFL-4 C8 Corvette transmission fluid should always be shaken vigorously prior to adding fluid to a vehicle in order to disperse the additives throughout the fluid. The fluid has a shelf life in the sealed bottle of three years. (Fig. 9)

Fig. 9

Track Fill Information

M1L Transmission and Z51 RPO – Vehicles equipped with M1L transmissions and Z51 models will need an additional two liters of transmission fluid added before track use. Transmissions will need to be identified as Die 1, Die 2 or Die 3.

GM does not condone tracking M1L-equipped vehicles without the Z51 RPO. If a customer decides to track the vehicle anyway, the transmission will need an additional two liters of fluid added before track use.

M1M and MLH Transmission – Vehicles equipped with M1M or MLH transmissions do not require a track fill with additional fluid.

Die 3 Cases – All vehicles equipped with an M1L, M1M or MLH transmission and a Die 3 case do not require a track fill with additional fluid. Refer to Bulletin #23-NA-156 for information on identifying a Die 3 case.

For more details on Corvette factory-covered maintenance, refer to Bulletin #24-NA-081.

– Thanks to Marty Leach

Updated July 30, 2024