Costco is always the cheapest gas around here. Unfortunately it’s located a bit to far away to be my usual stop. But when I’m over there I always fill up.
When I lived in Seattle there were five costcos within half an hour of our house. Now, we have to drive an hour and a half to either the Louisville or new Lexington store. And their gas is cheap for the area they are in, but still more expensive than where we live, so we pass. We used to always gas up at costco.