Is the JASO-MA needed for Jap./shared sump bikes? Reading seems to indicate this designation means the oil is compatable with a wet clutch and is something to look for. I know Mobil and Amsoil for motorcycles have this desig. what are some others?
Since JASO-MA is a new spec I doubt you will see many oils claiming to meet it.
I think Amsoil 10w40 does. But meeting a new spec doesn't automatically mean that the oil is better.
For example, some SH oils are superior to some SL oils for engine protection. Yes, SL is the new spec, but that doesn't mean it is superior to SH oils in all cases.
JASO MA is essentially a test to measure how much torque the oil can transfer through a wet clutch, so in that respect it is better than JASO MB, which is also considered a motorcycle oil.
Most any 15w-40 diesel oil will work in a wet clutch motorcycle, by the way, since they aren't friction modified.