Interesting. So here in Canada what is done at MOST stations that only offer the 3 tiers of fuel (87, 89, 91) is they only get two types of fuel 87 that is mandated to have 10% Ethanol, and 91 which is ethanol free. Then the pumps themselves have a blender unit in it so if you choose 89 it blends the two together so you would get around 5% ethanol.
Years ago when Husky was the only station selling fuel with ethanol the refineries were only producing 87 as the lowest octane rating, so then Husky would add their 10% Ethanol and it would be a 90 octane regular fuel. Once the government mandated ethanol fuel the refineries were able to use an 85 octane base and add ethanol to get an 87 octane rating.
So from factory, no mods, no tunes, are you saying that I shouldn't be running 91 premium? We used to run a Husky station, before and after the ethanol mandate which is why I know about it.