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.