Remember the excitement you felt upon filling up your gas tank for the first time? Chances are, as your driving skills improved, your excitement for the task has worn thin. These days, a great deal on gasoline may be the gift you get giddy about. You’re not alone either, countless Americans turn to Sam’s Club and Costco, both of whom are notorious for their discounted gas prices.

But will you have to sacrifice the quality of gas you put in your beloved buggy? Keep reading to learn more about the quality of gas at Sam’s Club and Costco and whether you should pump or pass.

In This Article:

  • How Gasoline Quality is Determined

    • By Retailer
    • Deposit Control Additives
    • Station Maintenance
  • Sam’s Club Gas Quality Analysis

  • How to Buy Fuel at Sam’s Club (Is Membership Required?)

  • Costco Gas Quality Analysis

  • How to Buy Fuel at Costco (Is Membership Required?)

How Gasoline Quality is Determined

Despite common misconceptions, you will not benefit from using premium gasoline unless your car manufacturer recommends it. Instead, AAA recommends choosing standard, high-quality gasoline. There are three major factors that determine the quality of fuel: the gasoline retailer, deposit control additives used, and station maintenance.

By Retailer

There are three types of gasoline retailers in the U.S.: those owned by major oil companies, branded independent fuel retailers, and unbranded independent fuel retailers.

Retailers owned by major oil companies get gas directly from company refineries. Their profit and loss is part of the corporation. In 2007 major oil companies began leaving retail behind to focus on production and operations. According to NACS, an association for convenience and fuel retailing, less than 0.4% percent of gas stations are currently owned by major oil companies. Shell, one of the largest retailers of this type, has just 20 locations owned by major oil companies. 

Branded independent retailers brand their store with the one brand of gasoline they sell. All of those big-name gas stations you pass by every day are likely small businesses who have contracts allowing them to brand their stores with the brand of gas they sell. For example, your local Shell station is likely not a large chain, but rather a locally owned station branded with the type of gasoline they sell.

Unbranded independent retailers do not pay the surcharge branded retailers do, making them a lower priority for providers when supplies are low. On the other hand, unbranded retailers do not depend on one supplier, meaning they can shop around for the best prices. This type of retailer may also have their own brand of gas. For example, Costco sells their own brand of gasoline exclusively — Kirkland Signature.

Deposit Control Additives

Deposit control additives essentially help keep your engine clean. A clean engine increases the performance of your vehicle and reduces the emissions it produces. Each brand of gas is treated with a specific additive, but there are a few standards that help ensure quality.

EPA Standards: In 1995, the U.S. Environmental Protection Agency (EPA) set a standard for the lowest additive concentration allowed in gas. This standard remains in place for anyone selling gas in the U.S.

Top Tier Standards: 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.

According to a AAA study, engine carbon deposits are reduced by 19 times with Top Tier gas. As a result, drivers may experience better drivability (less engine hesitation and knocks), better fuel economy, and fewer emissions.

The best part? Top Tier gas costs an average of just three cents more than non-Top Tier brands. Currently, each of the following retailers sells gasoline which is Top Tier licensed:

  • 76
  • Aloha
  • ARCO
  • Beacon
  • BP/Amoco Ultimate
  • BP Regular
  • BP Silver
  • Break Time
  • Cenex
  • Chevron
  • Conoco
  • Co-op
  • Costco Gasoline
  • CountryMark
  • CountryMark Plus
  • Diamond Shamrock
  • Esso
  • Express
  • Exxon
  • Hele
  • Holiday
  • Kwik Star
  • Kwik Trip
  • Kwik Trip Express
  • Mahalo
  • Marathon
  • Metro Petro
  • MFA
  • Mobil
  • OAAI
  • Ohana Fuels
  • Petro-Canada
  • Phillips 66
  • Puma Energy Caribe
  • QT
  • Quik Trip
  • Road Ranger
  • Shamrock
  • Shell
  • Shell (Canada)
  • Shell (Puerto Rico)
  • Sinclair
  • Standard
  • Sunoco Ultratech
  • SuperAmerica
  • SuperFuels
  • Tempo
  • Texaco
  • Tri-Par Qwik Stop
  • Valero

Station Maintenance

Once retailers receive their shipment of gas, they must take many steps to ensure the gas that reaches your tank is of the highest quality, as gas contaminated with sediment or water could wreak havoc on your vehicle. This includes maintaining the lines through which the gas flows. Larger retailers will likely have their station maintenance information available online. If your retailer of choice does not, you can contact them directly to see if they follow standard station maintenance guidelines.

Sam’s Club Gas Quality Analysis

Sam’s Club products, including gasoline, are backed by their satisfaction guarantee.

While little information regarding Sam’s Club Gasoline is available, we do know that they are operated by Walmart. In 2016, Walmart cut ties with their long-time gasoline provider, Murphy USA. During this time, Walmart expressed an interest in opening more fuel stations under their own name, but further information has yet to surface online.

*We submitted an inquiry to the Media Relations department at Walmart on June 13, 2017. At the time of publishing, we have not received information regarding fuel quality.

How to Buy Fuel at Sam’s Club (Is Membership Required?)

About 15 percent of Sam’s Club locations do not require a Sam’s Club membership to purchase gas, but all locations require a membership to receive the gas discount price. See if your local Sam’s Club requires a membership here.

  • Cost of membership: You can purchase a standard ‘Sam Savings’ personal or business membership for $45 a year or a ‘Sam’s Plus’ membership for $100, which includes additional benefits such as extended shopping hours and cash rewards for annual purchases over $500 (fuel purchases are excluded from this program).
  • Payment Methods Accepted for Gas Purchases: Sam’s Club MasterCard, which offers 5% cash back on gas purchases, Walmart MasterCard, Walmart and Sam’s Club gift cards, cash, check, debit cards, and most major credit cards can be used at Sam’s Club fuel centers.
  • Find a Sam’s Club Fuel Center near you.

Costco Gas Quality Analysis

Costco is an unbranded independent fuel retailer. Who supplies Costco gas? Its gas is sourced from major refineries and distributors in each region. Further, Costco gas stations follow these protocols to ensure the gasoline you purchase is clean.

Costco is a licensed Top Tier brand that uses Kirkland Signature Gasoline, which contains five times the additives required by the EPA. 

How to Buy Fuel at Costco (Is Membership Required?)

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

  • Cost of membership: A Costco membership costs $60 a year for a basic ‘Gold Star’ or business membership and $120 a year for an ‘Executive’ membership that includes additional discounts on some services and a 2% cash back reward on all travel-related purchases, including gas.
  • Payment Methods Accepted for Gas PurchasesCostco Visa, which offers 4%
  • cash back on gas purchases,  Costco Cash Cards, Visa, and most debit/ATM cards are accepted at Costco gas stations.
  • Find a Costco Gas Station near you. (Show filter options and select “Gas Station”)

In Summary

If you’re looking to fill your tank on the cheap, both Costco and Sam’s Club offer enticing prices, but the quality at Costco is top of the line. As a Top Tier licensed gas brand, Costco offers the same gasoline every single time — Kirkland Signature gasoline. The quality of Sam’s Club gasoline may be just as impressive, but without any verifiable information, we can’t know for sure.