That does make me wonder at times, as it is only down to the refinement of the fuel. I could understand it if it was like it used to be with the 4 star leaded and unleaded. And you had the 2 star for mowers and mopeds. But now I use E10 in my mower as well.
I don't know how my 1982 Datsun is going to fair with E5 or E10 though. When leaded was done away with, I just adjusted the carb and timing. Didn't even need to have new valve seats either. But thats a project for the near future.