The parameters of HD oils are classified according to the API system (American Petroleum Institut). European manufacturers also follow this system.
Designations are two-letter. The first letter characterizes the range of application:
- S = Service, intended for petrol engines;
- C = Commercial, designed for diesel engines.
The second letter in alphabetical order characterizes the type of oil.
The highest grades of oils are SG oils for gasoline engines and CE oils for diesel engines (according to the API specification).
Attention: Engine oils clearly marked by the manufacturer as oils for diesel engines are not suitable for gasoline engines. There are oils that are suitable for both gasoline and diesel engines. In this case, both specifications are indicated on the packaging (e.g. SG/CE).
European oil producers also adhere to "SSMS"- specifications. The CCMS classification takes into account the peculiarities of the European technology for the production of oils and therefore is becoming increasingly important. Oils for gasoline engines are distributed depending on the grade into classes from G1 to G5; for passenger car diesel engines, CCMC-PD1 oil and high-quality CCMC-PD2 oil are available.