Also consider some stations carry a layer of water at the bottom of the stations' tanks (above the pick up pipe) so they do not pay for idle inventory. They adjust the water level with alcohol. If they do a poor job you get water in the tank or over alcohol. If you wonder how you have melted fuel hoses, now you know. Impossible to prove.

Stick with stations that have service garages. Less likely to employ cashiers who double duty as fuel adjusters.