Japanese Automobile Standards Org.

JASO, as their full title suggests, is the organization responsible for establishing standards within the Japanese automotive market (which often overflows into the lubricants industry). It was JASO, along with the AAMA (American Automobile Manufacturers Association) that helped to create ILSAC (International Lubricant Standardization and Approval Committee) which plays an integral role in setting the minimum performance standards for motor oils and lubricants.

Since ILSAC has its roots in a cooperative arrangement between JASO and the AAMA, it's role is very much influenced by what JASO wants. So, JASO plays a role in the standardization of lubricants testing and performance criteria. In addition, JASO sets it's own, individual performance standards for lubricants such as the JASO MA and MB specifications for motorcycle oils.