I go to Costco for 2 reasons. First, it's much cheaper, second, they don't except cash at all so when the gas comes in the big containers on a truck, the guy pay off the driver to put some regular into super and so on. I have this friend who used to be one of those drivers and he said that almost all if not all gas stations he went to, the attendant gave him a 20 or a 50 so that he mixes the gas a little. I don't feel like paying the super price for regular, if you know what I mean. I did hear that Chevron uses some additives but here most stations are leased and because of that the dudes mix the gas a little.