Are Some Brands of Gas Better Than Others?

AAA’s tests show quality gasoline keeps engines 19 times cleaner

AAA Newsroom

When your tank is on empty and your car is running on fumes, it seems that any gas station will do. Keep in mind, however, that the quality fuel you normally use may not be the same as the fuel at the closest station.

AAA has revealed that tests uncovered significant differences in the quality of gasoline sold at fuel retailers in the United States. AAA used an independent laboratory to compare gasolines that meet Top Tier™ standards—often marketed as containing enhanced, engine-cleaning detergent additives—with gasoline brands that do not participate in the Top Tier program. Among brands tested, non-Top Tier gasolines caused 19 times more engine deposits than Top Tier brands after just 4,000 miles of simulated driving. These carbon deposits reduce fuel economy, increase emissions and negatively impact vehicle performance, particularly on newer vehicles.

What is Top Tier?

In 1996, in an effort to address emissions issues related to engine deposits, the Environmental Protection Agency established a minimum detergent level all gasoline must contain. While this level of detergent helped minimize engine deposits, some automakers felt the standard did not go far enough to ensure their engines met the emissions and performance criteria for which they were designed. The Top Tier fuel program was created to formulate and recommend fuels containing higher concentrations of additives that reduce engine deposits.

Will non-Top Tier gasoline damage a vehicle?

No, but gasoline that meets Top Tier standards will keep an engine cleaner and, therefore, maximize the vehicle’s performance and fuel economy. You won’t damage your vehicle if you don’t use a Top Tier gasoline, but your vehicle may not perform as well as it could, and you may drive fewer miles on each gallon of gas.

AAA Newsroom

How do retailers purchase and formulate gasoline?

Premium gas: wise choice or waste of money?

See the Answer

Base gasoline is the same across all brands. Only when detergent additive packages are added to gasoline tanker trucks—typically in a ratio between one quart and one gallon per 9,000 gallons of gasoline—do variations between brands occur. Some brands add just the minimum level of detergent additives mandated by the EPA, some add proprietary formulations of additives, and some add detergent packages that meet Top Tier performance standards.

AAA’s recommendations

  • For optimal vehicle performance and fuel economy, drivers should use a gasoline that meets Top Tier standards whenever possible. Find out which brands are Top Tier.
  • Follow your vehicle owner’s manual and use the correct fuel for your vehicle. Many consumers associate fuel quality with the octane of the fuel (regular vs. premium), which is incorrect. Top Tier retailers adhere to standards in all grades of fuel.
  • If you experience a rough idle, especially when the engine is cold, or hesitation during acceleration, it might be caused by the quality of fuel. Try changing to a Top Tier gasoline for several fill-ups.
  • Shop around. It is possible to purchase a Top Tier fuel for only pennies more per gallon. While it may be less convenient in some situations, long-term it will save money through better fuel economy and reduced need for repairs.

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