GMC vehicles generally require Dexos-certified motor oil, with Dexos1 Gen 2 for most gasoline engines and Dexos2 for Duramax diesels. The exact viscosity you should use depends on your specific engine and climate, so always follow the owner’s manual.
GMC, like other GM brands, standardizes oil specifications to protect engines, emissions systems, and warranties. Knowing which Dexos spec applies and the recommended viscosity helps you pick the right oil and maintain peak performance across GMC’s lineup. The guide below explains the two main Dexos specifications and how to determine the correct viscosity for your model.
Key oil specifications used by GMC
The oil you put in a GMC should be labeled Dexos and match the engine type. The list below summarizes the two main specs you’ll encounter on GMC vehicles.
- Dexos1 Gen 2: The standard specification for most current GM gasoline engines. Oils meeting Dexos1 Gen 2 are designed for turbocharged and modern engines and are suitable for passenger cars and light trucks in GMC lineups.
- Dexos2: The specification used for Duramax diesel engines and other high-demand engines. Oils meeting Dexos2 cover diesel and certain gasoline needs and help with soot control and combustion stability.
Oil manufacturers and service centers will use Dexos1 Gen 2 or Dexos2 based on the GMC engine in your vehicle. Always verify that the oil you buy carries the correct Dexos certification and the correct viscosity as recommended in the manual.
How to determine the right viscosity for your GMC
Operating conditions and engine design influence the viscosity you should use. The following guidance helps you confirm the right grade for your GMC.
- Check the owner's manual or the warranty guide for the recommended viscosity (for example 0W-20, 5W-30, or 0W-30). This is the definitive source for your model-year and engine family.
- Look at the under-hood oil fill cap or the oil specification decal on the engine for Dexos requirement and the grade. Some caps or decals indicate Dexos1 Gen 2 or Dexos2 with the grade.
- Ask a GMC dealer or a certified mechanic if you’re unsure, providing your VIN or model-year to confirm the right oil type and change interval.
In short, use Dexos-certified motor oil in the grade specified by GM for your exact GMC model and engine. The right oil helps protect emissions systems, maintain fuel economy, and preserve warranty coverage.
Practical steps to maintain your GMC oil program
- Identify your engine type and model-year to confirm Dexos requirement (Gas or Diesel).
- Consult the owner’s manual or GM Owner Center for the recommended viscosity and Dexos specification.
- Choose an oil that is Dexos-certified and matches the grade specified (e.g., Dexos1 Gen 2 0W-20).
- Ensure the service interval and filter are appropriate for the oil chosen; update any service reminders in the vehicle’s infotainment or your records.
Following these steps ensures you stay within GM’s guidelines and protect your GMC engine’s performance and warranty.
Summary
GMC requires Dexos-certified motor oil, with Dexos1 Gen 2 for most gasoline engines and Dexos2 for diesel engines such as Duramax. Always verify the exact viscosity and Dexos specification from your owner’s manual or a GMC dealer. Using the correct oil type helps engine longevity, emissions control, and warranty compliance.