(KTXL) — Many people flock to warehouses like Costco and Sam’s Club with high hopes of getting the best deal on the price of fuel. Although both offer similar savings, there’s a difference in the quality of gas they pump.

The most notable difference between Costco and Sam’s Club is that one provides Top Tier gas while the other does not.

“Not all gasoline is created equal,” Consumer Reports wrote in March 2022. “There is plain old regular, and then there is regular gasoline that meets a higher standard, known as Top Tier.”

According to Top Tier’s website, the fuel was “developed by some of the leading automotive and heavy-duty equipment manufacturers.” It is intended to reduce deposit buildup on fuel injectors and intake valves, which can improve your vehicle’s engine performance, responsiveness, and fuel economy.

In 2016, AAA conducted a study that revealed that Top Tier gasoline keeps engines 19 times cleaner.

In response to increasing levels of carbon deposits in modern engine designs, AAA reported that the Environmental Protection Agency mandated a minimum level of detergent — which helps keep your engine clean — for all gasoline sold in the U.S. in 1996. Top Tier fuel uses more detergent additives than the EPA requires.

Continued fuel use without the Top Tier additive package could result in 2% to 4% lower miles per gallon, increased emissions, and a greater chance of maintenance issues, according to AAA.

While both Costco and Sam’s Club offer unleaded, premium, and diesel fuels (here’s how to know which you should be getting), only Costco offers Top Tier fuel.

If you don’t have a Costco membership, you can still find Top Tier gas at other stations.

“Yes, Top Tier gas is worth the extra money,” CarFax reported. “The benefits are not a myth.”

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While Top Tier fuel may cost a bit more, you’re likely to save more overall at the pump if you fill up at a warehouse store — like Costco and Sam’s Club — than at a regular gas station.

Patrick De Haan, head of petroleum analysis at GasBuddy, told Consumer Reports that gas at warehouse stations is typically anywhere between 5 cents and 25 cents cheaper per gallon than at other gas stations.

“And when prices rise, they hold their prices down for longer,” he added.