Back when I bought a 2001 Kawasaki Mojave four wheeler I found the owner's manual had not been updated to 2001 specs. Because the quad originally came out as an early release 1986 model and had no updates throughout its production, they kept the same antiquated oil rating in the manual. I don't recall what it was off the top of my head but it was API SD or something and we are now into API SG, I believe.
Anyway my point is, oils will continue to progress and I'd really be surprised if Yamaha did not recommend the latest, most advanced type of oil.
Anyway my point is, oils will continue to progress and I'd really be surprised if Yamaha did not recommend the latest, most advanced type of oil.