Filip75 is correct, but he has not explained WHY. Bascially I stay away from discount places as there are problems with their fuel. Same with older stations & again same reason. True they get it from the same petrol tankers we see on the hwys, but often the discout places are sometimes a bit shaddy & have some diesel mixed in with regular fuel. How they do this I do not know, but it has been found out by inspectors after a lot of checking which might take a number of yrs.
Above all is that so many of them have underground tanks that are leaking out fuel & sucking in underground waters. When inspected then they have to change, but sometimes it is still above the level of needing to be changed to all new underground tanks.
You can sport the safer ones due to all new & modern pumps, obviously new asphalt & often the building is new. As for what make they sell I never worry only I will not touch anything that is with a grain or corn touch in it & you have some places in the States that sell this less costly petrol though it is well marked--------after all it will ruin a modern m/c..