How many quarts of transmission fluid does a 6.6 Duramax take?
About 15 quarts for a full transmission service on a 6.6 Duramax with the Allison 10-speed automatic; 12–13 quarts if you’re only draining the pan and refilling without replacing the internal filter.
The Duramax 6.6L is paired with an Allison 10-speed automatic in most GM heavy‑duty pickups. Fluid capacity can vary by model year and by whether you perform a full service (pan drain plus new filter) or a simpler drain-and-fill. The figures below reflect common practice and should be used as guidelines until you confirm the exact specification for your vehicle.
Factors that influence capacity
Several factors can affect the amount of transmission fluid you need for a service.
Model year and transmission variant
GM uses different 10‑speed variants across generations (such as 10L80 and 10L1000). Some variants may have slightly different fill volumes or service procedures, which can influence the total capacity you’ll need.
Typical capacities by service type
Below are common figures for a Duramax 6.6L with an Allison 10-speed automatic, depending on whether you replace the filter during service.
- Full transmission service with filter replacement: about 15 quarts
- Drain and fill only (no filter replacement): about 12–13 quarts
These are general guidelines for typical configurations. Always verify the exact spec for your year and transmission code in the owner's manual or GM service literature.
Fluid type and maintenance tips
Use the recommended automatic transmission fluid for the Allison 10‑speed in GM trucks, typically Dexron VI or GM-approved equivalents. Do not mix fluids, and refill to the correct level using the proper procedure and torque specifications on pan bolts and any filters.
Summary
For a 6.6 Duramax with the Allison 10‑speed automatic, plan on about 15 quarts for a full service (pan drain plus new filter) and roughly 12–13 quarts if performing a drain-and-fill without changing the filter. Always consult your specific year/model manual or GM service literature to confirm exact capacities for your vehicle, and perform maintenance with proper care to ensure transmission reliability in demanding use.
How many quarts of transmission fluid does a Duramax take?
Silverado 2500 Duramax often faces transmission overfill and incorrect fluid type issues during maintenance. When replacing the transmission fluid and filter, drain the pan completely and replace the filter. Use the manufacturer-recommended fluid type and capacity—typically around 13 quarts but verify your manual.
What kind of transmission fluid does a 6.6 Duramax take?
Dexron ULV transmission fluid
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 goes in a 6L80 transmission?
The 6L80 transmission fluid capacity is 12.2 to 12.4 quarts for a total fill. For a typical pan drop and filter change, the capacity is approximately 6.5 quarts, though this can vary and it's best to check the fluid level after adding the initial amount and running the engine. Always use Dexron-VI ATF and add fluid gradually until the proper level is reached.
This video demonstrates how to perform a 6L80 transmission fluid and filter change: 1mTrick Shift GarageYouTube · Nov 9, 2023
Fluid capacity
- Total fill capacity: 12.2 to 12.4 quarts
- Pan drop and filter change capacity: Approximately 6.5 quarts, but this can vary
How to fill
- Ensure the vehicle is on level ground.
- Add an initial amount of fluid (start with about 5-6 quarts for a pan drop).
- Start the engine and run it in Park for a few minutes.
- Check the fluid level on the dipstick and add more fluid as needed to reach the correct mark.
Important considerations
- Use Dexron-VI ATF: Only use Dexron-VI or a compatible synthetic fluid, as using the wrong fluid can damage the transmission.
- Check the level: The total capacity figures are for a complete overhaul. After a simple pan drop, you will not need to add the full 12+ quarts. Always check the dipstick to get the right level.
- Some models differ: A Corvette, for example, does not have a dipstick. Instead, it uses a level control plug in the bottom of the pan to set the fluid level.
You can watch this video to see how to check the 6L80 transmission fluid level: 59sTrick Shift GarageYouTube · Nov 22, 2023
How much fluid does a 6.6 Duramax Allison transmission hold?
What is the Oil Capacity of a Duramax? The 6.6 liter Duramax oil capacity is 10 quarts — a massive amount of oil.
