API - American Petroleum Institute

Whether an oil is suitable for gasoline or diesel engines

API Service Level Category

Since 1924, the American Petroleum Institute has been a cornerstone in establishing and maintaining standards for the worldwide oil and natural gas industry.

This defines whether an oil is suitable for gasoline or diesel engines.

Gasoline engines: The service level category contains two letters. The first letter, S, indicates the oil is for gasoline engines. The codes are as follows:

• SN: For vehicles manufactured after 2010
• SM: Vehicles manufactured between 2002-2009
• SJ: Vehicles manufactured before 2001

Diesel engines: The first letter, C, indicates the oil is for a diesel engine. The codes are:

• CJ-4: Four stroke high speed diesels manufactured from 2010
• CI-4: For vehicles built between 2002 and 2010
• CH-4: Vehicles built between 1998 and 2002

For full details consult the API Motor Oil finder.