Do fuel additives really clean your engine or is it all marketing hype? --- Sean, Felton, Calif.
Marshall Brain Answered:
The detergents put into gasoline really do keep an engine and the fuel system cleaner. So much so that in the U.S. The EPA requires the addition of gasoline detergents. According to this page: "EPA requires the use of additives to control the formation of engine and fuel supply system deposits in all U.S. gasoline. An interim program has been in place since 1995 which requires the use of detergents to control intake valve deposits (IVD) and port fuel injector deposits (PFID) in gasoline engines..." Without these additives, engine performance suffers over time.
One common additive is called polybutene amine. It helps to keep deposits from forming in the fuel system and on intake valves. Another is Polyether Amine, which may also help to eliminate deposits inside the combustion chamber.
Recently there has been a move on the part of car and fuel manufacturers to create a higher level of detergent additives. This is called Top Tier gasoline. According to the site, "TOP TIER Detergent Gasoline is the premier standard for gasoline performance. Six of the world's top automakers, BMW, General Motors, Honda, Toyota, Volkswagen and Audi recognize that the current EPA minimum detergent requirements do not go far enough to ensure optimal engine performance." See this page for details.
See also: How Gasoline Works