Short answer
dexos1 Gen 3 is General Motors’ engine oil specification for most of its gasoline engines. GM published it in 2021 and it replaced dexos1 Gen 2 for licensed products from September 1, 2021. It starts from the ILSAC GF-6 test set and adds GM’s own engine and bench tests, and only oils that GM has licensed may carry the dexos1 mark.
Where dexos1 Gen 3 came from
GM introduced the original dexos1 specification for the 2011 model year, followed by Gen 2 in 2017. Gen 2 was largely a response to low-speed pre-ignition (LSPI), the abnormal combustion event that small turbocharged direct-injection engines can suffer at low rpm and high load.
Gen 3 arrived in 2021 alongside the ILSAC GF-6 era. Trade reporting at launch described it as incorporating GF-6 tests and elements of updated ACEA testing, then layering on GM-specific requirements, including a revised LSPI test, a GM fuel economy test and a GM oxidation and deposit test in place of the industry Sequence IIIH.
What the specification asks of an oil
Beyond the ILSAC baseline, dexos1 Gen 3 tightens several limits that matter in modern GM gasoline engines. Reported examples include stricter evaporation (Noack volatility) and sulfated ash limits, along with tests aimed at piston deposits, oxidation and LSPI.
The specification is not a viscosity grade. GM engines may call for dexos1 Gen 3 oil in 0W-20, 5W-30 or other grades, and the grade in the owner’s manual still has to be matched separately.
Licensing and the dexos mark
dexos1 is a licensed specification, so a product cannot simply claim to meet it. Oil marketers submit test data to GM, and approved products receive a license number and the right to show the dexos1 logo. GM publishes a list of currently licensed products on its dexos website.
After Gen 3 took effect, GM allowed Gen 2 licensed oil already in the supply chain to sell through for a limited time. Gen 3 oils are described as backward compatible with earlier dexos1 applications when the correct viscosity grade is used.
How to use it when choosing oil
Start with the owner’s manual or the oil fill cap, which state both the dexos requirement and the viscosity grade. Then confirm the specific product appears on GM’s licensed list or carries the dexos1 Gen 3 mark on the current label.
If you have a newer turbocharged GM engine, the dexos1 Gen 3 requirement is especially relevant because LSPI protection is one of the reasons it exists. Keep receipts showing the oil used if the vehicle is under warranty.
Frequently asked questions
Can I use a dexos1 Gen 3 oil in a car that calls for Gen 2?
GM describes Gen 3 as backward compatible with earlier dexos1 applications, provided you use the viscosity grade the manual specifies.
Is an API SP oil the same as dexos1 Gen 3?
No. API SP and ILSAC GF-6 are part of the baseline, but dexos1 Gen 3 adds GM’s own tests and requires a GM license.
Where can I check whether an oil is licensed?
GM maintains a list of licensed dexos products on its official dexos website, and licensed bottles show the dexos1 logo.
General maintenance information. Always follow your vehicle or equipment manufacturer’s requirements and the current product data. Questions? Email [email protected].
