I burn premium in all my small engines and old IH gasser tractor. The tractor seems to run cooler and will not "diesel" when shut off hot when running premium. Iw will "diesel" with 87.
I also run 93 octane in my 90 Subaru, it runs better ( need all the hp I can get ) and I get better mileage, about 50 more miles per tank. So the money is about the same.
Of course at $2.37/GAL yesterday, not cheap...
Ben