The API performance system - which continues to be developed based on the recommendations of ILSAC (International Lubricant Standardization and Approval Committee) - was introduced in 1947.
In Europe - in the case of cars and commercial vehicles - the API system is rarely applied, as the engines of vehicles for use on public roads must comply with ACEA standards and the directives of the engine manufacturers. The API performance level standards remain applicable to engines used in agricultural machinery, certain types of vehicle used by the construction industry and in earth-moving machinery. The currently valid engine oil specifications are as follows:
API performance levels for (US-manufactured) Otto engines
| SH |
For engines manufactured before 1997. This can be used for any earlier specifications (API SF, SG). |
| SJ |
Uniform lubricant for American Otto engines manufactured before 2001. |
| SL |
Came into force in 2001, very advanced performance level meeting stricter requirements. Can be used in all US-manufactured Otto engines. |
API performance levels for diesel (commercial vehicle) engines
| CF (earlier CD) |
Medium performance level introduced in 1994 for supercharged engines. |
| CF-4 |
Medium performance level substituting the earlier API CE category. |
| CG-4 |
Advanced category introduced in 1995 for all previously manufactured engine types. |
| CH-4 |
Category with extremely strict requirements, applicable in all of the current American "heavy diesel" engine types. Characterised by enhanced anti-wear protection and carbon black dispersibility. |
| CI-4 |
Meets requirements for EGR engines complying with US emission standards Introduced in 2002 and enforced from 2004. Characterised by stricter test bench requirement (timing gear wear, carbon black dispersibility, piston cleanliness, stability of oxidation and viscosity properties) than for CH-4. |
The API compression-ignition type category specifically relates to large (heavy-duty) commercial vehicle diesel engines. American bench tests do not cover diesel engines, therefore there is no API performance level that can be applied to European high-performance diesel cars. In such cases the ACEA B categories provide proper engine protection.
