Top Tier detergent gasoline retailers in the United States include Shell, Exxon, ARCO, BP and Chevron. Most U.S. gas stations offer Top Tier gasoline for all grades of gas, and toptiergas.com has a comprehensive list of retailers. Costco Wholesale also offers Top Tier gasoline at its pumps.
Top Tier gasoline contains higher levels of detergent than regular gasoline. Higher detergent levels help to prevent build-up of unwanted deposits in combustion chambers, fuel injectors and valves and prolong the life of a vehicle's engine. Several major automobile manufacturers, including Audi, BMW, General Motors, Honda, Mercedes-Benz, Toyota and Volkswagen, recommend the exclusive use of Top-Tier detergent gasoline.