Quick answer: the GM 6.6L Duramax V8 diesel takes 10.0 qt (9.5 L) of oil with a filter change. GM specifies SAE 15W-40 diesel oil with the API CJ-4 or CK-4 designation; below 0°F (-18°C), use SAE 5W-40.
| Engine | Oil capacity (with filter) | Oil type | Required rating |
|---|---|---|---|
| 6.6L Duramax V8 diesel (LML, LGH, L5P) | 10.0 qt (9.5 L) | 15W-40 (5W-40 below 0°F) | API CJ-4 or CK-4 |
Use diesel oil, not gasoline oil. GM warns that oils without the CJ-4 or CK-4 designation can damage the diesel particulate filter (DPF).
Oil capacity by year
| Model year | Oil capacity (with filter) | Oil type |
|---|---|---|
| 2016 | 10.0 qt (9.5 L) | 15W-40 (5W-40 below 0°F) |
| 2019 | 10.0 qt (9.5 L) | 15W-40 (5W-40 below 0°F) |
| 2020 | 10.0 qt (9.5 L) | 15W-40 (5W-40 below 0°F) |
| 2022 | 10.0 qt (9.5 L) | 15W-40 (5W-40 below 0°F) |
| 2024 | 10.0 qt (9.5 L) | 15W-40 (5W-40 below 0°F) |
| 2025 | 10.0 qt (9.5 L) | 15W-40 (5W-40 below 0°F) |
We read the 2016, 2019, 2020, 2022, 2024 and 2025 supplements; all list the same capacity and grades. The 2016 supplement also covers the 2.8L Duramax (Colorado/Canyon) at 6.0 qt.
Recommended oil type
GM’s 6.6L supplements say to use SAE 15W-40 viscosity grade engine oil. When it is very cold, below -18°C (0°F), use SAE 5W-40 to improve cold starting. Only oils designated API CJ-4 or CK-4 (alone or combined with other API designations) are acceptable.
Other engines in the same trucks
- Silverado 1500 and Sierra 1500: 5.3L / 6.2L V8 8.0 qt, 3.0L Duramax 7.0 qt.
- The 2022–2025 Silverado HD 6.6L gas V8 takes 8.0 qt (7.6 L), per the main HD owner’s manual.
Sources and how we checked
We read the “Capacities and Specifications” and “Engine Oil” sections of GM’s Duramax Diesel Owner Manual Supplements, published on GM’s official owner manuals site:
- 2016 Chevrolet and GMC Duramax Diesel supplement
- 2019 Chevrolet and GMC Duramax Diesel supplement
- 2020 Chevrolet and GMC Duramax Diesel supplement
- 2022 Chevrolet and GMC Duramax Diesel supplement
- 2024 Chevrolet and GMC Duramax Diesel supplement
- 2025 Chevrolet and GMC Duramax Diesel supplement
If your owner’s manual shows something different, follow your manual and tell us.
Last checked: October 26, 2026.
FAQ
How much oil does a 6.6 Duramax take?
10.0 qt (9.5 L) with a filter change, in every Duramax diesel supplement from 2016 to 2025 (LML, L5P).
What oil does a 6.6 Duramax use?
SAE 15W-40 diesel oil with the API CJ-4 or CK-4 designation. Below 0°F (-18°C), GM says to use SAE 5W-40.
Does the L5P take more oil than the LML?
No. GM lists 10.0 qt (9.5 L) for the 6.6L in every supplement we read.
Can I use dexos oil in a Duramax 6.6?
GM’s 6.6L supplements call for API CJ-4 or CK-4 diesel oil, not gasoline dexos oils. Using other oil can damage the diesel particulate filter.
Where does GM publish the Duramax oil data?
In the separate Duramax Diesel Owner Manual Supplement for Silverado HD and Sierra HD; the main truck manual refers to it.