GM Engine-Oil Specifications
GM uses the dexos trademark for licensed engine oils. A licensed product carries the dexos mark and a GM license number; an oil merely described as “suitable for” or “recommended for” a dexos application is not necessarily a GM-licensed product.
There is no single engine-oil requirement for every GM vehicle. The correct dexos specification, SAE viscosity grade and oil-change interval depend on the engine, model year and market. Always verify the current owner’s manual or service information for the vehicle concerned.
| Specification | Status | Application and compatibility |
|---|---|---|
| dexos1 Gen 3 | Current | GM’s mainstream gasoline-engine specification. It supersedes dexos1 Gen 2 and is backward compatible for applications that previously specified dexos1 or dexos1 Gen 2 when the correct viscosity grade is used. Current North American GM gasoline-vehicle manuals commonly specify dexos1 Gen 3. |
| dexosR | Current | A newer gasoline-engine specification, principally represented by higher-viscosity performance oils. GM states that dexosR meets or exceeds dexos2 and dexos1 Gen 2/Gen 3 performance and may be used for gasoline engines formerly requiring those specifications, provided the owner’s manual permits the viscosity grade. |
| dexosD | Current | GM’s light-duty diesel-engine specification. GM states that dexosD meets or exceeds dexos2 performance for diesel applications and replaces dexos2 for light-duty diesel use when the specified viscosity grade is selected. For example, current 3.0 L Duramax diesel documentation specifies dexosD. |
| dexos2 | Superseded transition specification | Originally a low-SAPS, long-life specification used across certain gasoline and diesel applications, especially in Europe. GM now directs gasoline applications formerly using dexos2 to dexosR and light-duty diesel applications formerly using dexos2 to dexosD, using the viscosity grade specified by the vehicle documentation. |
dexos1 Gen 3
dexos1 Gen 3 is the service specification for many GM gasoline engines. It is a licensed GM requirement, not simply an API or ILSAC claim, although licensed oils may also carry current API engine-oil service categories and ILSAC classifications. GM identifies dexos1 Gen 3 as backward compatible with earlier dexos1 and dexos1 Gen 2 applications.
dexosR
dexosR is the newer GM gasoline specification and replaces dexos2 for gasoline applications. The licensed-product list includes SAE 0W-40 and 5W-50 examples, illustrating why a dexosR oil must not be selected solely because it is newer: the required viscosity grade remains vehicle-specific.
dexosD
dexosD replaces dexos2 for GM light-duty diesel applications. The former statement that all Duramax diesel engines require API CJ-4 oil is obsolete and should not be used as a general rule. Diesel requirements vary by engine and model year; current GM documentation for the 3.0 L Duramax calls for dexosD, while other Duramax engines must be serviced to their own current manual and service-information requirements.
Superseded GM Engine-Oil Specifications
The following approvals remain relevant when interpreting older owner manuals, service records and product data sheets, but they are not the current starting point for oil selection.
| Specification | Historical use | Current context |
|---|---|---|
| dexos1 / dexos1 Gen 2 | Earlier GM gasoline-engine dexos specifications. | Superseded by dexos1 Gen 3; GM also recognizes dexosR as a backward-compatible gasoline successor where the proper viscosity grade is used. |
| GM-LL-A-025 | Long-life gasoline-engine approval used primarily in Europe. | Legacy specification, replaced in practice by later dexos requirements for the relevant vehicle. |
| GM-LL-B-025 | Long-life diesel-engine approval used primarily in Europe. | Legacy specification, replaced in practice by later dexos requirements for the relevant vehicle. |
Older GM long-life specifications should not be reduced to a single viscosity grade or a fixed drain interval. Where an older manual names GM-LL-A-025 or GM-LL-B-025, use the vehicle documentation and an appropriate current GM successor specification rather than assuming that an ACEA sequence alone is an equivalent approval.
GM Automatic-Transmission Fluids
DEXRON is a GM automatic-transmission-fluid family, not a universal fluid recommendation. Transmission design, model year and RPO code can change the required fluid even within one vehicle line. Use the exact fluid specified in current GM service information.
| Fluid | Status and use |
|---|---|
| DEXRON VI | Current GM service-fill fluid for many conventional automatic transmissions. GM identifies it as the replacement for earlier DEXRON II(E) and DEXRON III(H) automatic-transmission applications. It is not a substitute where the vehicle specifically requires DEXRON HP, DEXRON ULV, a dual-clutch fluid, CVT fluid or another dedicated lubricant. |
| DEXRON HP | Application-specific high-performance ATF used in certain GM eight-speed automatic transmissions. It must not be replaced with DEXRON VI unless GM service information expressly allows it. |
| DEXRON ULV | Application-specific ultra-low-viscosity ATF used in certain GM ten-speed automatic transmissions. It is not a substitute for DEXRON III or DEXRON VI. |
| FFL-4 | Dedicated fluid for the Chevrolet Corvette C8 dual-clutch transmission. It is not interchangeable with conventional DEXRON fluids. |
Legacy DEXRON designations
Type A, Suffix A; DEXRON II(D); DEXRON II(E); and DEXRON III(F), III(G) and III(H) are historical GM ATF designations. They are useful for identifying the original requirement in older documentation, but should not be treated as current universal specifications. For an older automatic transmission originally calling for an earlier DEXRON fluid, GM identifies DEXRON VI as the service replacement; manuals, transfer cases, manual transmissions and power-steering systems may have separate fluid requirements.
For more context on application-specific ATFs, see why “universal ATF” needs verification and DEXRON VI, HP and ULV transmission fluids explained.