What kind of oil does a 2015 Chevy Silverado 3500 6.6 take?
The recommended oil for the 2015 Silverado 3500 HD with the 6.6L Duramax diesel is Dexos2‑approved synthetic diesel engine oil, typically 5W‑40.
Use an oil that meets GM Dexos2 specification and API CK‑4. Always verify with your owner's manual or your GM dealer for your exact engine and climate, but 5W‑40 Dexos2 is the standard choice for this model year and engine.
Oil specifications and options
Below are the official guidelines and the typical options you will see on product labels when shopping for Duramax diesel oil.
- Dexos2‑approved 5W‑40 synthetic diesel engine oil (GM specification 6094M), suitable for Duramax 6.6L engines from 2011–2016.
- API CK‑4 (or CJ‑4/CJ‑4‑compatible lubricants that also carry Dexos2 approval) in appropriate viscosities; the primary recommendation remains 5W‑40 Dexos2.
- If you are in a cold climate, some brands offer Dexos2 options in 0W‑40; confirm compatibility with Dexos2 and CK‑4 requirements in your manual.
In practice, the simplest and most reliable choice is Dexos2 5W‑40 synthetic diesel oil. If Dexos2 is not available in your area, consult a GM dealer for acceptable alternatives that still meet CK‑4/Dexos2 compatibility, and avoid mixing oil types.
Where to buy and brands
Look for Dexos2 on the label and choose a reputable brand that offers a 5W‑40 diesel oil formulated to meet Dexos2 specifications.
- Mobil 1 ESP Formula 5W‑40 Dexos2
- Amsoil Diesel Heavy‑Duty 5W‑40 Dexos2
- Valvoline Premium Blue Diesel 5W‑40 Dexos2
- Shell Rotella Dexos2 5W‑40 (T6 or comparable Dexos2‑rated product)
Always ensure the bottle explicitly lists Dexos2 approval and that the oil is suitable for diesel engines in heavy‑duty applications. Climate, driving conditions, and maintenance intervals may influence the exact grade you choose beyond the standard 5W‑40 Dexos2 recommendation.
Maintenance notes
Follow GM’s recommended oil‑change intervals for your Duramax 6.6L and use the same Dexos2‑approved oil for top‑ups. Regularly check oil level and condition, especially after extended or severe use, and use the same Dexos2‑approved oil to maintain engine protection and warranty coverage.
Summary
For a 2015 Chevy Silverado 3500 HD with the 6.6L Duramax, the standard oil is Dexos2‑approved synthetic diesel oil, with 5W‑40 as the typical viscosity. Verify the exact specification in the owner’s manual and choose a reputable brand that clearly states Dexos2 approval and CK‑4 compatibility. Always follow maintenance schedules and climate‑adjusted recommendations from GM or your dealer.
