> Should it be a given, that regardless of milage or > driving conditions, etc. that after 21 years its safe > to say that the fuel injectors are in need or cleaning > or replacment. Sorry for being so long winded here, but here are the facts as to what fuel injector cleaners really are, and why. Also some information on what gasoline is made of and how it relates to fuel injector cleaners. Fuel injector cleaners consist of common solvents which for the most part are already present is gasoline. Contrary to popular belief, gasoline is not a single substance but consists of a mixture of light hydrocarbons. The largest components of gasoline are Heptane, Hexane, Octane ( this is where the term "Octane Rating" comes from by the way ), and Cyclohexane. There are also smaller amounts of other things such as Benzine, Toluene, and Xylene. Benzine, Toluene, and Xylene are commonly used elsewhere as solvents and to a certain extent will dissolve deposits in fuel injectors. This is not the reason that they are included in gasoline, but IS the reason that they are put in small cans and sold as "fuel injector cleaners". Additionally, just for information, there are trace amounts of Naphthalene, which is commonly known as "Moth Balls", present is gasoline. The final components of gasoline, which are present most everywhere in the United States, are called oxygenating compounds. These things aren't related to the topic of injector cleaners, but are interesting to show how the gas companies distort the truth. These so called oxygenating compounds are usually nothing more than common Ethanol, which is present in beer, wine, and booze. IMHO the real reason for putting Ethanol in gasoline is simply that including Ethanol, which dissolves water and itself dissolves in gasoline, is to permit the gasoline companies to include a certain amount of WATER in the gas in a way that consumers cannot detect. It may be hard to believe that the gasoline companies would do this, but indeed it is a fact and the presence of water can be confirmed analytically. The thing to note here about fuel injector cleaning additives ( the "better" ones at least ) is that they almost always composed of things that ARE ALREADY IN gasoline. The things that are already in gasoline are the Benzine, Toluene, and Xylene mentioned earlier. The sum total of Benzine, Toluene, and Xylene in gasoline can be fifteen to twenty percent of the total gasoline ingredients. Since up to twenty percent of the gasoline is ALREADY the same ingredients that are sold as "fuel injector cleaners", there is little sense or benefit in adding an additional eight ounces or so to ten or more gallons of gas in the fuel tank. Doing so in the case of an eight ounce can of "fuel injector cleaner" being poured into ten gallons of gas already in the tank, adds only about three percent more "fuel injector cleaner" to what is already there. Other things commonly sold as "fuel injector cleaners" are even worse than what is described in the previous two paragraphs. This type of "cleaner" is nothing more than alcohol ( Ethanol or Methanol ) which will have almost zero effect on crud deposits in car fuel systems. Sometimes the ingredients are spelled out on cans of this stuff in plain language ( Toluene, Xylene, Methanol, etc. ), but mostly, if the ingredients are listed at all, scientific terms are used to make it hard for the average customer to figure out what is really in them. Sorry for being so long winded here, but I just hoped to set the record straight on fuel injector cleaners. George Ryerson, Akron Ohio '83 Yellow painted "D"