The API classification was introduced by the AMERICAN PETROLEUM INSTITUTE (API) with the Motor Oil Licensing and Certification System (EOLCS).

Engine Oil Guide

1. Performance

API S: Oils designed for gasoline engines will be applied to vehicles with engines classified under API “S” (Service).                

API C: Oils designed for diesel engines are classified according to API “C” (Commercial). Exact descriptions of current and obsolete API classes can be found in the tables for gasoline and diesel engines.  

2. Viscosity class.

This is the definition of liquid and fluidity at certain temperatures. Manufacturers’ recommendations according to the prescribed SAE viscosity grade may vary.

3. Energy saving.

The designations “Resource Conserving” (RC) and “Energy Conserving” (EC) apply to vehicles with petrol cars and vans. The use of these oils can reduce perspiration consumption throughout the car park. For these oils, the following applies primarily.

4. Multiple performance levels Lubricants designed for diesel engines may also be suitable for gasoline engines. For these oils, the “C” classification is applied, followed by the “S” classification. Class “C” oils were originally developed for diesel engines and therefore may not meet all the requirements of gasoline vehicle manufacturers.