It's not that they require an old rating, it's that they want to be sure that there are no friction modifiers.
To be 100% sure of that, for a conventional automotive oil, SH is the highest rating.
Newer oils are also fine as long as they carry the JASO-MA.
But.....
There are still plenty of acceptable oils that do NOT carry JASO-MA and do not contain friction modifiers.
Likewise, my clutch gave me problems when I was running Motul Twin-Synd 20w50, which does carry JASO-MA. I replaced the clutch, and within 500 miles it was slipping again. Changed the oil to Castrol GTX 20w50 and it's been fine since (about 250 miles).
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- Rich
2006 1600 Classic
Member CORVA, BRC
Patriot Guard Rider
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