That's interesting information. While I was fully retired, I bought almost all of my gas from Costco. Now that I'm working part time, it's not convenient, so I've been purchasing gas from a local, non-major station. I did a bit of googling after seeing your post. Sounds like Costco is one of the best, BJ's not so much. The question is if that really makes much difference to an average modern auto? If I'm driving a Porsche needing 93 octane and costing a lot, maybe I'd be concerned. I'll have to do a bit of research and see if someone makes a bottle of additive to add to lower quality gas to bring it up to a higher standard each fill up.