Keep in mind....
Keep in mind that the quality of ALL gasoline is federally mandated. Meaning that all of it has to meet a very strict set of guidelines. That doesn't mean that you won't get some to perform better with your particular set up than others, just that it all met the federal specs. We blend up ULCQ (unleaded contol quality) gasoline for the government and the automakers several times a year. This gasoline is what your estimated mileage that you see on the window sticker of a new car was achieved with.
In general, buy gas from places that have high traffic and therefore, high turnaround on their product. The gasoline is fresher, higher octane, higher vapor pressure etc....
We don't have Sunoco in my part of the country but all the big names still sell 93 octane. I understand that 91 is the highest octane in other places.
