Can I use a costco cash card for gas even though I'm not a member?

Must be a member

Yes, if you have a Costco gift card you can use Costco like any member.

I don't think so; they need a Costco membership number to unlock the pump.

I was given a Costco gift card that a member got as a perk and I was wondering the same thing but I don't think they let you in or use gas if you're not a member

I think you have have to be a member to get gas.