Sunoco always did that. Don't know how old you are, but I remember as a kid (I'm in my mid 30's) Sunoco had this dial on the nozzle to select your "special blend" My grandfather used to think that the dial did nothing, that it was just marketing.
Originally Posted by JanGeo
If you use Sunoco I think it gets blended at the nozzle by pumping the High Test and the Regular in two separate lines to the nozzle.
The Harley I used to have required 91 or it would ping real bad on hot days, after sitting in traffic, or if I didn't have enough rpms.
I never thought much about this perceived problem myself. A 5 gallon tank made it largely moot, and I usually put in 4 gallons at a time. I can see how it might be a problem if it wasn't driven much and topped off often in a bike that had a higher compression.