I think we are talking different things.
I want to know what does the MA2 "tick" bring to the "characteristics/properties" of a modern oil, that would otherwise meet the required oil API "tick" (and are relevant to motorcycle engine that does not have a wet clutch or shared gearbox).
I think its not related to the cat (as API oils are compatable with cats, nothing special here).... I understand the additive package etc will be different because of wet clutch and gearbox requirements (that are not relevant to our bikes)....
So.... my mind goes to "why is the BMW oil spec for this bike include a JASO MA2"?
I know lots of "air head" owners have used non Jaso MA oils in the past without issues. I've found nothing related to engine heat, load, temperature, metalurgy etc that explains this.
The other mind bogling thing is how basic/old is a API SJ rating......
I'm not asking what oil to use in my bike, I am trying to understand the relevance of the Jaso rating as it stands in a modern boxer without a wet clutch/gerabox.... and "because BMW said so" is not an answer to this.
Though, I do appreciate the effort you went to regarding yoir post.... thankyou.