There's a lot of value to joining Costco, like saving money on groceries and the household essentials you need. But if you don't have a large household or don't cook often, then it may not make financial sense to spring for a Costco membership. You should know, though, that if you're not a member of Costco, it means you risk missing out on the warehouse club giant's low-cost fuel.

Costco is known to have some of the cheapest gasoline in town. And as an added perk, Costco's gasoline is TOP TIER™ certified. This means it's designed to improve performance, which could set you up to get better mileage out of your tank.

But while you usually have to be a member to fill up gas at Costco, there's one lesser-known way you can get around that rule.

When you want the best gas without committing to a membership

If you're convinced that a Costco membership won't benefit you, then you may be inclined to just pay more for gas at another station rather than join to fill up on the cheap. And the good news is that with the right credit card, you can enjoy perks like extra cash back on fill-ups from any gas station you frequent. Check out our list of the best gas rewards credit cards.

But actually, there's one way to get around the membership requirement at Costco's fuel stations -- paying with a Costco Shop Card.

The Shop Card is Costco's version of a gift card. You have to be a member of Costco to purchase one, but you don't need to be a member to use one.

If someone buys you a Costco Shop Card, you simply show it at the door, and you'll be allowed to shop in the store even if you don't have a membership. And similarly, you can use a Shop Card to fill up your tank at a Costco fuel station.

So if you truly have no need for the inside of the store, you could always ask a friend or neighbor to load up a Costco Shop Card you reimburse them for. That gives you access to low-cost fuel without the commitment of a membership.

Consider whether a membership makes sense for the gas savings alone

It's one thing to have someone buy you a Costco Shop Card on occasion, or to get one as a gift and use it for gas. But you probably don't want to bug your neighbor to buy you one weekly so you can fill up regularly at Costco. So there may come a point when it's time to crunch the numbers and see if it makes sense to join Costco for the gas savings alone.

Let's say you typically buy 10 gallons of gas per week. If Costco's gas is $0.20 cheaper per gallon than the next most affordable fuel station in your neighborhood, then you're looking at saving $2 per weekly fill-up. If you fill up 50 weeks out of the year (allowing for a couple of vacation weeks), you're saving $100 on gas.

In this situation, a Costco membership does make sense, because the Gold Star membership only costs $65 per year. If you spend $65 but save $100, you'll be ahead by $35.

Plus, there are many other benefits to joining Costco, like savings on travel packages, home improvement services, and more. So even if you don't think you'll take advantage of the store's bulk grocery offerings, you might still enjoy having a membership. You can check out this list of credit cards that could help you enjoy even more rewards in the course of your Costco shopping.

Top credit card to use at Costco (and everywhere else!)

We love versatile credit cards that offer huge rewards everywhere, including Costco! This card is a standout among America's favorite credit cards because it offers perhaps the easiest $200 cash bonus you could ever earn and an unlimited 2% cash rewards on purchases, even when you shop at Costco.

Add on the competitive 0% interest period and it's no wonder we awarded this card Best No Annual Fee Credit Card.

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The Little-Known Way You Can Buy Gas at Costco Without a Membership was originally published by The Motley Fool