Sam’s Club & Costco Gas Quality: Pump or Pass?

Short Answer: Both Sam’s Club and Costco source their fuel from multiple suppliers instead of partnering with one major oil company. While Sam’s Club gas comes with the company’s Satisfaction Guarantee, Costco’s gas is TOP TIER certified, meaning that it has more deposit control additives than the EPA requires. For more information on the gas quality at Sam’s Club and Costco, as well as how to buy gas at both wholesale clubs, see below.

Sam’s Club Gas Quality

Sam’s Club operates independent, unbranded gas stations, meaning it does not source its fuel from a single oil company. The company assures the quality of its gasoline with the Sam’s Club Satisfaction Guarantee.[1] However, Sam’s Club gasoline is not licensed as TOP TIER (explained below).

Walmart operates Sam’s Club; and while it does not disclose its fuel suppliers, we do know that Walmart cut ties with its long-time gasoline provider, Murphy USA, in 2016.[2] Note that while Sam’s Club gas is not TOP TIER, the company may have its own additive formulation and testing process to ensure its fuel quality. Neither Walmart nor Sam’s Club disclose much information about maintenance at their gas stations, but the companies are required to follow the minimum guidelines set by the Environmental Protection Agency (EPA), the National Fire Protection Association (NFPA), state governments, and other regulatory bodies.[3][4]

How to Buy Gas at Sam’s Club

You must have a Sam’s Club membership to purchase fuel.[5] Previously, around 15% of Sam’s Club locations did not require a membership to purchase gas, but Sam’s Club no longer sells fuel to non-members.

Costco Gas Quality

Costco also operates unbranded gas stations, and while the company does not disclose much information about its fuel suppliers, its website states that its fuel comes from the same major refineries that supply all the gas stations in a given area.[7] The company follows strict protocols to ensure its gasoline is clean.[8] Costco is a licensed TOP TIER brand that sells its own formulation of Kirkland Signature Gasoline, which contains five times the deposit control additives required by the EPA.

Costco also boasts excellent station maintenance;[9] its trained attendants manage the fuel additives at each station, take regular take samples, and monitor nozzle flow rates.

How to Buy Gas at Costco

Costco gas stations are open only to Costco members or those customers paying with a Costco Cash Card.

  • Cost of membership: $60 per year for a basic “Gold Star” or business membership; $120 per year for an “Executive” membership, which offers a 2% cash-back reward (including gas purchases).[10]
  • Payment methods for gas: Costco Visa, which offers 4% cash back on gas purchases; plus Costco Cash Cards, Visa, and most debit/ATM cards

TOP TIER Gasoline Standards

In 1995, the EPA set a standard for the lowest additive concentration allowed in commercial gasoline.[11] However, in 2004, a group of automakers created TOP TIER gas, which includes a specific level and formulation of deposit control additives that exceed EPA standards.[12]

According to a study conducted by the American Automobile Association (AAA), engine carbon deposits are reduced by 19 times with TOP TIER gas. As a result, drivers may experience better drivability, better fuel economy, and fewer emissions. TOP TIER gas costs an average of three cents more per gallon than other brands, but it has become the standard for high-quality gasoline. In order for a retailer to be TOP TIER certified, it must include the proper additive formulation in all octanes, so you do not need to fuel your car with an octane rated higher than the car needs.

For more about TOP TIER licensees, see our articles on the gas quality at 76, ARCO, Mobil, Sunoco, and Valero.



  • Found a few Valero stations with Top Tier has tags on the pumps. Locations are from League City, Dickinson and Galveston. My 2002 Suburban purrs after drinking it. Can not believe the difference after the 1st tank. Have been using it fou about 2 months.

  • A. Young says:

    I just spent $1000 on my Ford 2011 Taurus because of contaminants in gas from Sam’s Club in Temple, Texas. I notified Sam’s Club.

    • Rebecca Turley says:
      First Quarter Finance logostaff

      Hi there,

      Many times, the source of the contamination with the gas occurs at the pump and not with the gasoline itself. You can file a complaint with the Texas Department of Agriculture to have the gas at that station tested. You may be able to receive reimbursement from the gas station’s insurer and recoup the cost of your vehicle repair.

  • I stopped by my Sam’s club in Portage, Michigan and they were having fuel delivered at the time. The worker asked the truck driver what type of gas it was and he replied British Petroleum (BP).

      • Lindsey Desmet says:
        First Quarter Finance logostaff

        Hello, Stephen! Sam’s Club gasoline is not licensed as TOP TIER. We have updated our article to include this information.