Couple things: We live near a large Marathon distribution center (big white tanks above ground and all that) in Lebanon. We see all of the tanker trucks coming and going, and they are from a multitude of companies, not just Marathon. I've heard that it "all comes up in the same pipeline, but some companies add a little of this or a little of that to their particular taste". Dunno, I'm not a fuel guy. Secondly, I've had great luck with Marathon fuel (completely unrelated to being near the depot. There's a Marathon about a mile from the depot, on 122, that charges the same as everyone else). We used BP for years, religiously. I switched to Marathon exclusively, and my work car (Mazda 3) went from 25 mpg religiously to 27-28mpg. Same driving, nothing else changed. I think that as long as you're buying from a station that has a reasonable amount of business, the fuel in their tanks is getting rotated enough that it shouldn't be an issue. A mom and pop shop out in the holler may give you problems, but when you're out there, you're probably out of options anyhoo. I don't like buying race fuel at the beginning of the season because in my mind, its been sitting in the tank collecting moisture all winter.