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Modern fuel injection systems may be far superior to old-timey carburetion in lots of ways, but they aren’t without their maintenance demands. For example, carbon and other deposits can build up over time on injectors, which can restrict fuel flow and prevent optimal atomization, affecting overall performance and fuel economy. This is particularly true when a car sits inactive for extended periods of time. Like, say, when there’s a global pandemic going on and you might not be commuting as often. Caterpillar injector
Newer vehicles featuring direct-injection systems raise even more concerns. That’s because direct-injection systems spray fuel directly into the chamber, whereas conventional port injection sprays fuel directly into the intake valve, which helps keeps the valves clean. If ignored, these deposits can gunk up injectors and inhibit flow, which in the long term, can cause excess wear and tear on your fuel system and engine, resulting in costly repairs.
Thankfully, quality fuel injector cleaners exist to prevent them from getting to that stage. These cleaners help by dissolving gunk, 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 vary, though most at a minimum include detergents, including PEA (Polyetheramine), the leading active ingredient that helps clean and clear away these harmful deposits and prevent clogging. Others feature lubricants for the upper piston rings on the cylinders that help seal the combustion chamber.
While the market for fuel system cleaners is vast and abundant, we’ve created a very short list of some of the top fuel injector cleaners you can buy. It’s important to remember that some are for gasoline engines only, others are just for diesel and a few will work with both. It’s always a good idea 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 60103
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. The company 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.
Like Red Line, Chevron claims its own exclusive formula, Techron, an additive the company 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 Fuel Injector Cleaner for Older Vehicles
Best Fuel Injector Cleaner for Older Vehicles
Liqui Moly 2030 Pro-Line Gasoline System Cleaner
When to comes to additives and cleaners, Liqui Moly is one of the best in the business, which is expected since it originates from Germany, a country known for its superior automotive products and engineering. Case in point, Liqui Moly’s Pro-Line Fuel System Cleaner, which is a professional grade fuel system cleaner that not only helps to clean out the tank, fuel pump assembly and lines, but injectors as well.
In addition to its high quality, pro-grade formula, it’s also inspected and rigorously 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. Lots of users claim that they could feel an overall difference with this product, including smoother idling, better throttle response and slightly improved fuel economy thanks to a cleaner combustion.
This Liqui Moly product is usable for gasoline vehicles of all makes and from all periods, though many classic car owners tout excellent results, particularly with older fuel injection systems. It is on the pricier side, but it’s very much a case of getting what you pay for.
Best for Vehicles with High Mileage
Best for Vehicles with High Mileage
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 10003
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.
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. However, it should be noted that fuel system and injector cleaners should not be used excessively as they can leave deposits on spark plugs and exhaust valves and cause more issues rather than solving them.
Generally, it’s suggested that you put the fuel injector cleaner in first, and then the gasoline. That’ll not only allow the fluids to mix when filling the tank, but it will also give an immediate strong shot of cleaner to the injectors when you start.
No. They’re similar, but they do different things. 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.
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.
Denso Diesel Injector Since picking up my first set of MicroMachine toy cars as a toddler, I knew I had a passion for automobiles embedded in my soul. After graduating from Rutgers University in journalism, I’ve devoted my career to becoming a professional photographer and emerging voice in the car industry with columns at Automobile Magazine, MotorTrend, Hagerty, DigitalTrends.com/Cars, GearPatrol, and beyond.