[P.K.]

As noted by others, the difference in performance might be marginal as the engine knock sensor will compensate for the lower octane fuel. The more important factor in my experience is the amount of ethanol in your fuel. After some research and personal experience, I would never put any amount of ethanol through my high output little engine. I have seen the results of ethanol on fuel tanks and systems. Storage is a big issue as well. Even with fuel stabilizers, corrosion from ethanol even in small amounts is bad. I recently drained the unstabilized 20 year old "premium" fuel from my Rolls Royce. Just for entertainment, I filled the fuel bowl and put the fuel pickup line on my 1974 Nissan pickup into a one litre container of my old fuel. To our amazement, the engine flashed up with no hesitation and sat idling away smooth and happy! Perhaps sitting in a vintage Rolls Royce was a privilege for the fuel, but in any case the fuel was unleaded and un "corned" - There you have it. PS. The old fuel is being used up in the lawn tractor and the Roller is getting fresh un-ethanolled premium 94 (Canada).