Most 2018 GMC models use synthetic Dexos oil for gasoline engines (often 0W-20), while diesel-equipped models use Dexos2 with appropriate viscosity. The exact specification depends on your engine and climate, so always verify in your owner's manual or with a GMC dealer.
Understanding the basics for the 2018 lineup
GM’s oil standard for gasoline engines is Dexos1 Gen 2, with common viscosities including 0W-20 and 5W-30 depending on engine design and operating conditions. Duramax diesel engines use Dexos2, typically with a heavier viscosity. Because there were multiple engines across GMC trucks and SUVs in 2018, checking the precise specification for your vehicle is important.
- Gasoline engines in the 2018 GMC lineup generally require Dexos1 Gen 2 synthetic oil, most often with a viscosity of 0W-20. In some engines or climates, 5W-30 may be specified.
- Diesel Duramax engines (such as certain Sierra 1500 configurations) typically require Dexos2 synthetic oil, commonly around 5W-40 or 0W-40, depending on the exact engine and GM guidance.
Bottom line: For gasoline-powered 2018 GMC models, Dexos1 Gen 2 is the standard; for diesel Duramax models, Dexos2 is used. Always confirm the exact viscosity for your specific model and environment.
How to confirm the exact oil specification for your 2018 GMC
To lock in the precise oil type and viscosity for your vehicle, use these steps. This ensures you meet GM’s requirements and protect engine longevity.
- Consult the owner's manual: Look in the "Lubrication" or "Maintenance" section for the recommended oil specification (Dexos1 Gen 2 for gasoline, Dexos2 for diesel) and the viscosity (0W-20, 5W-30, etc.).
- Inspect the oil fill cap and under-hood labels: Some engines display the required viscosity and specification on the cap or nearby labels.
- Check the GMC Owner Center or contact a GMC dealer: You can enter your VIN to retrieve the exact recommended oil for your vehicle.
- Consider climate and driving conditions: Very cold or very hot climates can influence the preferred viscosity (for example, 0W-20 for cold starts, 5W-30 in warmer or heavy-use scenarios).
Concluding note: Verifying the exact specification for your engine via the manual, cap labels, or a dealer ensures you use the proper oil and maintain warranty coverage.
Quick reference by engine type
The following broad guidance reflects typical GM practice for 2018 gasoline vs. diesel engines, but always confirm for your exact model and engine:
- Gasoline engines: Dexos1 Gen 2 synthetic oil, commonly 0W-20; 5W-30 may be specified in some cases.
- Diesel Duramax engines: Dexos2 synthetic oil, commonly around 5W-40 (or as specified by GM for the exact engine).
Conclusion: If you’re unsure, your best bet is to check the owner’s manual or contact a GMC dealer to confirm Dexos1 Gen 2 vs Dexos2 and the exact viscosity for your 2018 model and engine.
Summary: For a 2018 GMC, gasoline engines typically take Dexos1 Gen 2 oil with 0W-20 viscosity (or sometimes 5W-30), while diesel Duramax engines use Dexos2 oil (often 5W-40). Always verify the precise specification for your specific vehicle and operating conditions to ensure proper lubrication and warranty compliance.