dexos1 Gen3 is General Motors' current performance specification for gasoline-engine oils, layering extra protection tests (notably against turbocharger deposits and low-speed pre-ignition) on top of the API SP / ILSAC GF-6 baseline. A 5W-30 or 0W-20 oil is only correct for a dexos engine if it also carries the dexos1 Gen3 license.
Specification
dexos1 Gen3
Supersedes
dexos1 Gen2
Check a bottle label
If your manual lists dexos1 Gen3, use the
oil spec checker to compare the manual requirement with
what an oil bottle says. Need the source first? Start with the
owner's manual finder. Viscosity and approvals
are separate requirements.
Specification, not a grade
This is the clearest example of why viscosity is not the same as specification. Your GM engine may call for 0W-20, dexos1 Gen3 — that’s a grade (0W-20) and a specification (dexos1 Gen3). Both must match.
What dexos1 Gen3 adds
Building on the API SP and ILSAC GF-6A industry baselines, dexos1 Gen3 adds GM’s own tests — including stronger protection against low-speed pre-ignition (LSPI) in turbocharged direct-injection engines, and tighter limits on deposits and oxidation. It is GM-licensed: qualifying oils carry the dexos mark.
How to comply
Match the grade your manual lists and look for the official dexos1 Gen3 license on the bottle. If you can’t confirm both, choose a different oil or consult your dealer.
Frequently asked questions
Is dexos1 Gen3 just a viscosity grade?
No. It is a performance specification, separate from the viscosity grade. An oil must be a specific grade (e.g. 0W-20) AND carry the dexos1 Gen3 license to satisfy a GM engine that requires it.
Can I use a non-dexos oil that says "meets dexos"?
Look for the official dexos license mark, not just marketing wording. GM licenses specific products; "meets the requirements of" is not the same as being licensed. When in doubt, follow your owner's manual.