Short answer
dexos2 was a GM engine oil specification built on the ACEA C3 mid-SAPS category, used mainly in European GM gasoline and diesel engines. GM has since split that role: dexosD covers light-duty diesel engines such as the 3.0L Duramax, and dexosR covers certain gasoline engines that previously used dexos2. Owners should follow the dexos specification and viscosity grade printed in their current owner’s manual or supplement.
What dexos2 was
dexos2 launched around 2010 for GM’s European market, replacing the older GM-LL-A-025 (gasoline) and GM-LL-B-025 (diesel) long-life specifications. It was built on ACEA C3, a mid-SAPS category intended to protect diesel particulate filters and catalysts, with some added GM tests.
In North America dexos2 was also listed for some high-performance gasoline engines, which is why it is often associated with performance oils as well as European models.
dexosD for light-duty diesels
dexosD is GM’s light-duty diesel specification. GM owner documentation for the 3.0L Duramax inline-six calls for dexosD licensed oil, and the viscosity grade is set by the vehicle documentation rather than by the specification itself.
Larger GM diesel engines have historically followed API heavy-duty diesel categories rather than dexos, so check which requirement your manual actually lists before assuming dexosD applies.
dexosR for performance gasoline engines
dexosR is the newer gasoline specification that GM directs former dexos2 gasoline applications to. Licensed dexosR products have tended to be higher-viscosity performance oils, such as 0W-40 or 5W-50 grades, in line with the engines that use them.
Because dexosR and dexos1 Gen 3 both cover gasoline engines, the owner’s manual is the deciding document. Some GM performance engines list one, some list the other, and a few supplements have been updated after the vehicle shipped.
What to do if your manual says dexos2
Check GM’s current dexos website and any owner manual supplement for your vehicle, since GM has published updated guidance moving dexos2 applications to dexosD (diesel) or dexosR (gasoline).
Whatever specification applies, match the viscosity grade as well. A licensed oil in the wrong grade does not satisfy the manual’s requirement.
Frequently asked questions
Is dexos2 still licensed?
GM has moved dexos2 applications to dexosD and dexosR. Check GM’s official dexos site for the current status of any product.
Does the 3.0L Duramax use dexos1?
No. GM documentation for the 3.0L Duramax diesel specifies dexosD licensed oil in the grade shown in the manual.
General maintenance information. Always follow your vehicle or equipment manufacturer’s requirements and the current product data. Questions? Email [email protected].