In 2006, MA1 and MA2 were added as extra categories within the JASO MA specification. The main difference between these two categories is the higher friction performance MA2 oils are delivering. This meant that from 2006 on, motor oils that meet the T903:2006 standard can be divided into four specifications for 4-stroke motorcycle oils:
JASO MA: This is the standard specification for oils that are used within one oil system (where the engine, gearbox and clutch use the same oil). These oils don’t contain any friction modifiers.
JASO MA1: This is a lower standard specification for motorcycles that require different oils for the engine, gearbox and clutch.
JASO MA2: This is a higher standard specification for modern motorcycles. These oils are suitable for use in motorcycles that have catalytic converters in the exhaust system.
JASO MB: This is a lower standard specification for scooter engines.