How much fluid does a 6.6 Duramax Allison transmission hold?
The typical full-fill capacity is about 19 quarts (roughly 18 liters) of transmission fluid, including fluid in the torque converter. The exact amount depends on the model year and the specific Allison transmission variant used with the 6.6 Duramax.
Capacity overview by variant
Transmission configurations have varied across generations of the Duramax 6.6. In general, newer 10-speed Allison units carry a slightly higher total capacity than earlier 6-speed 1000 variants, and the stated figure can change if you drain the torque converter or perform a pan-only drain. The numbers below reflect typical service ranges reported by technicians and manufacturers.
- Allison 1000 six-speed variants (earlier Duramax 6.6 builds): roughly 17–19 quarts (about 16–18 liters) total capacity when fully filled.
- Allison 10-speed variants (newer Duramax 6.6 configurations): about 18–20 quarts (roughly 17–19 liters) total capacity when fully filled.
Note: Exact capacity can vary by VIN, transmission code, and whether you drain the torque converter. Always verify with the official GM service manual or your dealer for your vehicle.
Service and refill considerations
When planning a fluid change or refill, technicians consider the full capacity, including any fluid in the torque converter, and the correct procedure to ensure proper level and operation. Use the transmission fluid specification recommended by GM for your year and transmission variant.
- Perform a warm-up cycle, then check fluid level with the vehicle on level ground and in the required gear ranges.
- Decide whether to drain the torque converter. Draining it increases the total amount of fluid that must be added to reach the correct level.
- Replace filters/pan gasket as specified during a service to ensure optimal flow and sealing.
Overfilling can cause foaming and shifting issues, so follow the official fill procedure and consult a professional if in doubt.
Summary
In most Duramax 6.6 with Allison automatics, total fluid capacity when filled to specification sits in the high-teens to around 20 quarts, with exact figures dependent on the specific transmission variant and whether the torque converter is drained. For VIN-specific numbers, refer to the GM service manual or your dealership.
What transmission fluid does a 6.6 Duramax take?
Dexron ULV transmission fluid for 10-speed automatics. This is the factory recommended fluid for both 3.0L and 6.6L Duramax engines with the 10-speed automatic transmission.
How many quarts of transmission fluid does an Allison take?
Allison transmission oil capacity varies by model and service type, so always check your vehicle's manual for the exact amount. For a standard fluid and filter change, a 1000/2000 series transmission typically requires about 7.4 quarts, while a 3000/4000 series transmission requires about 19 quarts (excluding external lines and cooler). A full fill capacity will be higher than a partial fill, so final verification should always be done by checking the dipstick with the engine running at operating temperature.
Approximate capacities for common Allison transmissions
- 1000 and 2000 Series: A standard fluid and filter change usually requires around 7.4 quarts, though the total fill capacity is closer to 13 quarts.
- 3000 Series: A standard fluid and filter change (3000 RDS) requires about 19 quarts, not including external lines and the cooler.
- 4000 Series: A standard fluid and filter change (4000 Series) requires about 28-30 quarts.
- Filter only: For a main filter change only, the fluid loss is approximately 1 pint (0.47 liters) for 1000/2000 series and 2 quarts (1.9 liters) for 3000/4000 series transmissions.
Important considerations
- Check your manual: The final fluid capacity depends on the specific vehicle configuration and the presence of external lines and coolers. Always consult your vehicle's owner's manual or a service guide for the exact amount.
- Fluid level check: Always verify the final fluid level with the engine running at operating temperature. It is normal for the dipstick reading to be low until the transmission fluid circulates through the system after the initial fill.
- Fluid type: Use only Allison-approved fluids, such as those meeting the TES 295 or TES 389 specifications. For 10-speed transmissions, the recommended fluid is Dexron ULV.
How many quarts does a 6.6 l Duramax diesel hold?
What is the Oil Capacity of a Duramax? The 6.6 liter Duramax oil capacity is 10 quarts — a massive amount of oil. While oil capacity is one thing to consider when dealing with your engine oil, there's much more to think about, like other Duramax fluid capacities, oil factors and unique performance needs.
How much transmission fluid does a 2019 Chevy 2500hd hold?
The 2019 Chevy 2500 transmission fluid capacity varies by transmission type: the Allison 1000 (6-speed diesel) requires a 12.7-quart total fill and a 7.4-quart service refill, while the 6L90 (6-speed gasoline) has a 10.5-quart total fill for the standard version and 12.4 quarts for the HD cooler version. For the 10-speed 10L80, the total system capacity is approximately 12.08 quarts.
2019 Chevy 2500 transmission fluid capacity by transmission
This video demonstrates how to change the transmission fluid in a 2019-2026 Chevrolet/GMC 2500: 56sMechanic ModeYouTube · May 29, 2025
- Allison 1000 (6-Speed, with 6.6L Duramax L5P diesel engine):
- Total Fill: 12.7 quarts
- Service Refill: 7.4 quarts
- 6L90 (6-Speed, with 6.0L gasoline engine):
- Total Fill: 10.5 quarts (standard)
- Total Fill: 12.4 quarts (with HD cooler)
- 10L80 (10-Speed):
- Total Fill: Approximately 12.08 quarts
