Originally Posted by apecush
Might want to re-check your sources there. Norcal (SF) refiners are chevron, shell, conocophillips, valero, and tesoro. Costco purchases from these refiners.
I've never had an issue with Costco fuel...or any fuel for that matter.
Perhaps I have it the other way around. Anyway, I'd trust Costco over the value brands such as Valero, Arco, no name gas stations and others around here.
I still prefer Chevron if I can find it. 76 Stations are disappearing... Rather disappointing as they are one of the few places that sold 100 octane unleaded at the pump at some stations.