Everyone loves cheap gas, but not everyone loves to pay for a club membership to get one, so have the best of both worlds! According to Bargaineering (new window), it is possible to get Costco gas without having a Costco membership as long as you have an American Express card.
All you have to do is swipe your regular American Express card when it asks for you to swipe your Costco card, then swipe the credit card you want to pay with. I have not tried this, but I have read numerous accounts of it working.
Apparently it works because Costco has a Costco Amex card, and that card can be used as proof of membership, however the machine is trained to only read the line of code that says it’s an Amex card and nothing else. Therefore when you swipe a regular Amex card the machine thinks that it’s a Costco member Amex card.
Locate a Costco nearby, try it out and let me know how you enjoy your (roughly) 10 cent discount on gas!