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Fuel injection systems are light years away from old-fashioned carburetion, except for one thing: Carbon and other deposits can block the spray of fuel from injector nozzles, just like they could inhibit fuel delivery in a carburetor. And because of the precision of fuel injection, a little gunk can hurt a lot, resulting in a rough-running engine, a loss of power and reduced fuel economy. Dirty injectors can cause excess wear and tear on your fuel system and engine, which can result in costly repairs. Fuel Pump Gear
Before it gets to that stage, a quality fuel injector cleaner can help by dissolving gunk and cleaning fuel lines and injector nozzles—all for just a few bucks a bottle (prices vary and some are very inexpensive).
The formulations of some fuel injector cleaners include detergents, including PEA (Polyetheramine), which cleans and clears away harmful deposits and clogs. Others feature lubricants for the upper cylinders (above the piston rings, where oil cannot reach). Some are for gasoline engines only, some just for diesel and a few will work with either fuel, so make sure to fully read the instructions.
Reduces rough idle, engine surge, hesitation, and spark plug fouling
Cleaning injectors, carburetors, valves and combustion chamber
Contains synthetic upper cylinder lubricant
All gasoline and diesel engines
Stabilizes gas and diesel fuels up to 2 years
Red Line SI-1 Complete Fuel System Cleaner
A lot of the fuel injector cleaners on the market have similar formulations. Red Line SI-1 Complete Fuel Cleaner has its own patented formula, an upper-cylinder lubricant, a high concentration of PEA for maximum cleaning and a blend of high-temperature and low-temperature detergents. Beyond that, SI-1 enhances fuel stability, inhibits the formation of gum and varnish and according to the manufacturer, can lower the engine’s fuel octane requirement. Red Line charges a premium for this product, and while some users swear by it, other users say they get similar results from far more affordable competitors. Red Line admits its strong suit is prevention more than deep cleaning of heavy fuel system deposits.
Chevron Techron Concentrate Plus has a lot going for it: A well-known brand name, wide distribution (available online, in auto parts stores, department stores, grocery stores and most Chevron gas stations) and a low price. And they sell a lot of it (it’s Amazon’s best-seller among fuel injector cleaners). Like Red Line SI-1, Chevron Techron Concentrate Plus is a total fuel system cleaner, going beyond just injectors. And like Red Line, it claims its own exclusive formula, Techron, an additive Chevron has used in its gasoline for decades, in addition to the detergent PEA. Where it differs from Red Line is that it’s for gasoline engines only (Chevron sells a separate fuel injector cleaner specifically formulated for diesels).
Best Imported Fuel Injector Cleaner
Best Imported Fuel Injector Cleaner
No, we don’t mean this is for imported cars only. Liqui Moly Jectron is from Germany but is sold here in North America. And that matters because it’s inspected and tested by Technischer Überwachungsverein (Technical Inspection Association), an independent German testing firm. TUV approval means it’s been tested for safety and that it meets manufacturer claims. Liqui Moly says users can expect smoother idling, better throttle response, cleaner combustion and that Jectron will eliminate starting problems, hesitation and stalling. Owners of older vehicles are among the product’s biggest fans, saying they get great results, but Jectron is still geared towards post-1975 vehicles with catalytic converters. It is not intended for use in diesel engines and, as usual, there are some users who say it didn’t work for them.
Higher-mileage vehicles that haven’t been obsessively maintained can be a special case. From 75,000 miles up, there’s a greater chance that carbon, sediment and gums will keep injector nozzles and other components from operating efficiently. Gumout High Mileage is formulated with one of the highest concentrations of PEA on the market to attack large caked-on deposits. Don’t be surprised if that takes repeated uses, which is why Gumout makes their cleaner available in a six-pack of six-ounce bottles. As with most of these cleaners, it takes a tank or two to feel the effect, and in older cars possibly even longer. Fortunately, the price per ounce still works out to be among the lowest.
Lucas Upper Cylinder Lubricant and Injector Cleaner
Lucas Upper Cylinder Lubricant and Injector Cleaner does work on gasoline vehicles and vehicles with carburetors, but it is specifically formulated to make it a superior product for diesel. It lubricates the fuel rail and diesel injectors and neutralizes the harmful engine effects of low-sulfur diesel fuel for vehicles that were not designed to accommodate it (the kind used almost exclusively on American roads since 2006). The price is right, too, with less than 20 dollars for a 32-ounce bottle working out to one of the lowest prices per ounce on the market.
Reduces rough idle, engine surge, hesitation, and spark plug fouling
Cleaning injectors, carburetors, valves and combustion chamber
Contains synthetic upper cylinder lubricant
All gasoline and diesel engines
Stabilizes gas and diesel fuels up to 2 years
We considered a broad range of end-user ratings and evaluations by multiple testers, and some of our own experiences cleaning older fuel injection systems (primarily on vehicles from the 1980s) with these products.
We rate fuel injector cleaners based on the following weighted metrics:
Yes. Used regularly according to manufacturer instructions, fuel injector cleaners remove harmful deposits of carbon, sediment and gum, cleaning the nozzles of fuel injectors and other parts of the fuel system. Removal of those deposits aid in performance and fuel efficiency. Even if there aren’t measurable gains, these cleansers help keep your fuel system clean and maintained.
That depends on the severity of the deposits in the vehicle and the detergent and other chemical strength of the cleaner. Follow manufacturer recommendations for use and don’t expect one treatment to clear out years of caked-on gunk. Regular, repeated treatments should show results.
That depends on the product. Some recommend adding the cleaner every time you fill your fuel tank—at least for a while. Others have longer intervals between use and are meant to be used at tune-up time or as preventative measures.
Generally, it’s suggested that you put the fuel injector cleaner in first, and then the gasoline. That’ll give an immediate strong shot of cleaner to the injectors when you start.
Fuel injector cleaners are different from gasoline treatment. They use a stronger formulation of cleaning agents than gasoline treatments, but do not contain octane boosters or other types of fuel additives meant to boost performance.
Low Speed Diesel Engine A car-crazy California kid, I’ve been writing and talking about vehicles for 25 years on TV and radio, in print and online, including AAA magazines in Arizona, Oklahoma, Northwest Ohio, South Dakota and the Mountain West, as well as BBC Autos. I serve as vice president of the Western Automotive Journalists, a professional group for automotive writers based in San Francisco, and have no relation to McKeel Hagerty of Hagerty Classic Insurance, who is younger, better looking and wealthier.