Top Tier Gasoline Worth the Extra Price, Study Shows

An analysis by AAA reveals that gas with detergent additives can keep an engine running smoothly

A person pumping gas Photo: iStock

Not all gasoline is created equal. There is plain old regular, and then there is regular gasoline that meets a higher standard, known as “Top Tier.” The difference between the two is significant, based on an extensive study conducted by AAA in 2016. Testing from that membership group revealed that consumers would be wise to factor the quality of the gasoline into their purchase decision, even if it costs a little more.

What Is Top Tier Gas?

Gasoline is essentially a shared commodity, often stored in common containers until it is purchased by a major retailer. After that, the retailer treats the gas with a specific additive, thereby giving the fuel its brand identity. But are these additives just a dosage of marketing hype?

more on fuel economy

Top Tier gasoline was developed in 2004 to go beyond the minimum standard for detergent additives to better protect increasingly sophisticated engines from carbon buildup and deposits on the intake valves—which can result in a rough idle, acceleration hesitation, knocking/pinging, and reduced fuel economy.

Over the past 20 years, engines have become far more precise, operating under tighter tolerances and at higher compression ratios, while targeting cleaner emissions and improved fuel economy. To achieve these goals, several major automakers—Audi, BMW, Ford, General Motors, Honda, Mercedes-Benz, Stellantis, Toyota, and Volkswagen—have united in support of Top Tier gas, specifically recommending it to their owners with the goal of preserving their engines’ original performance and emissions over time.

Keeping things simple for consumers, when a participating retailer sells Top Tier fuel, all octane grades from regular to premium gasoline and diesel must adhere to the Top Tier standards. So it is not necessary for drivers to upgrade to premium to gain the cleansing benefits. 

A Ford 2.3-liter engine being tested on a dynamometer.

Top Tier Retailers

Retailers include 76, Aloha Petroleum, Arco, Beacon, Breakaway, Cenex, Chevron, Citgo, Conoco, Costco, CountryMark, Diamond Shamrock, Express Mart, Exxon, Fast Fuel, GetGo, HFN, Harmons Fuel Stop, Hele, Holiday, Kwik Star, Kwik Trip, Marathon, Meijer, Metro Petro, Mobil, Ohana Fuels, Phillips 66, QT/Quik Trip, Reeders, Road Ranger, Rutter’s, Shamrock, Shell, Simonson, Sinclair, Sunoco, Texaco, Valero, Value America, Wow, and Win Win.

Check this updated list of Top Tier retailers.

Intake valve comparison showing a new valve compared with valves after a 100-hour engine test.

Gas Test Findings

For the test, an independent engine testing lab that specializes in fuel analysis operated an engine continuously for 100 hours on a cycle to represent 4,000 real miles of use. The engine was then disassembled and photographed, and its key components were weighed and measured to determine the thickness of carbon deposits. Six fuels were used, randomly selected and split among three basic gasoline sources and three Top Tier.

The results showed that on average, non-Top Tier gasoline had 19 times more carbon deposits on injectors, on intake valves, and in the combustion chamber than Top Tier gasoline.

AAA also found Top Tier gasoline can have a cleansing effect, reducing intake valve deposits by 45 to 72 percent when used over a 5,000-mile interval. Variation in the results is attributed to the detergents used by different brands.

Further, analyzing gas prices over a 12-month period found just a 3-cent price difference between non-Top Tier and Top Tier gasoline.

Bottom line: For the nominal investment, this study shows that motorists would benefit from using Top Tier gasoline as their primary fuel.


Jeff S. Bartlett

A New England native, I have piloted a wide variety of vehicles, from a Segway to an aircraft carrier. All told, I have driven thousands of vehicles—many on race tracks across the globe. Today, that experience and passion are harnessed at the CR Auto Test Center to empower consumers. And if some tires must be sacrificed in the pursuit of truth, so be it. Follow me on Twitter (@JeffSBartlett).