Top Tier is a performance standard for gasoline, backed by major automakers. Since the 1990s, the Environmental Protection Agency has required a minimum level of detergent for all gas sold in the United States. But some automakers say the EPA standards are not good enough. To be considered Top Tier, the gasoline must have a higher concentration of detergent added to it.
Some brands use the minimum level of detergent additives required by the EPA, others add proprietary formulations of additives and others use detergent packages to meet Top Tier performance standards.
Top Tier gasoline was developed in 2004 to go beyond the EPA standards 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, eight automakers-Audi, BMW, Fiat Chrysler Automobiles, General Motors, Honda, Mercedes-Benz, 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.
About a third of gas stations currently meet the Top Tier fuel standards, including retailers known for inexpensive gas. Places that sell Top Tier gasoline will often display a logo to let customers know (see image, below). Top Tier stations include 76, Aloha Petroleum, Amoco, ARCO, Beacon, BP, Break Time, Cenex, Chevron, CITGO, Conoco, Co-op, Costco, CountryMark, Diamond Shamrock, Entec, Esso, Express, Exxon, Holiday, Kwik Star Stores, Kwik Trip, Mahalo, MFA, Mobil, Ohana Fuels, Petro-Canada, Phillips 66, PUMA, QT, Quik Trip, Road Ranger, Shamrock, Shell / Shell V-Power, Sinclair Standard, SuperAmerica, SuperFuels, Tempo, Texaco, Tri-Par, and Valero.
Using an independent engine testing lab that specializes in fuel analysis, AAA sought to answer the question: Is “Top Tier” gasoline worth the price? 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 marketing hype?
For its test, the lab operated an engine continuously for 100 hours on a cycle to represent 4,000 real-miles of use. The engine was then disassembled, photographed, and its key components 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, Top Tier gasoline had 19 times fewer carbon deposits on injectors, intake valves, and in the combustion chamber when compared to regular gasoline. Over time, those engine deposits can cause problems for your car. AAA says if you use gas without an enhanced additive package for a long time, it can lead to a 2% to 4% reduction in fuel economy, increased emissions and negatively impact the driving experience.
AAA also found Top Tier gasoline can have a cleansing effect, reducing intake valve deposits by 45 to 72% 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 three cent price difference between non-Top Tier and Top Tier gasoline. So if you’re filling up a small car with 12 gallons of gas, that’s an additional 36 cents on average to keep your car running at its best. For the nominal investment, the study demonstrated that motorists would benefit from using Top Tier gasoline as their primary fuel.
Given the technological trend toward more sophisticated engines, EPA should consider raising the minimum detergent standards to ensure all drivers benefit from the type of performance and longevity promised by Top Tier fuels.