Top Tier gasoline is a fuel performance standard based on deposit control additives and designed to minimize carbon deposit build-up on critical engine components like air intake valves and injectors. It is recognized as a high-quality fuel performance specification developed by several leading automotive and heavy-duty equipment manufacturers. The following are the characteristics of Top Tier gasoline:

• In order to be certified as Top Tier, a gasoline must pass a series of performance tests that demonstrate specified levels of deposit control on intake valves, fuel injectors, combustion chambers, and prevention of intake-valve sticking.
• Gasoline marketers agree when they sign on to the Top Tier program that all their grades of gasoline meet these standards.
• Premium grade gasoline may have yet higher levels of detergent additives.

Several automakers, including BMW, General Motors, Fiat Chrysler Automobiles, Ford, and Honda, support Top Tier gasoline. Although vehicle owners are not required to use Top Tier gasoline, it can help ensure that engines last as long as they could. According to a study by AAA, Top Tier gasoline can reduce build-up deposits on fuel injectors and on intake valves, restore engine performance, vehicle responsiveness, and fuel economy, and help prevent the loss of critical fuel economy. The study also found that non-Top Tier gasoline had 19 times more carbon deposits on injectors, on intake valves, and in the combustion chamber than Top Tier gasoline.