How To Clean Fuel Injectors On A Diesel

The vast majority of vehicles sold today have fuel injectors, which work by delivering precise amounts of gasoline or diesel fuel to each cylinder exactly when it's needed for optimal combustion. These injectors can get dirty over time, and depending on your vehicle, its condition and the fuel you feed your car, truck or SUV, your injectors may need to be cleaned intermittently in order for them to operate at their best.

Your best bet for faithful long-term performance is to use top-tier gasoline from reputable stations, to drive your vehicle sympathetically and keep up with scheduled maintenance. Treat your engine right and you may never need these specialized cleaners at all. That said, you might do everything right and still have issues with your engine's fuel injectors, or with clogged fuel lines or fuel filters. In such cases, a special cleaning agent designed specifically for this task can be among the easiest ways to clean your dirty fuel injectors and restore performance.

"Fuel injector cleaners, and more general fuel system cleaners, are fuel additives that help you clean the fuel system," says Fabio Rosato, founder of Roadologist.com, a site dedicated to helping readers improve their automotive knowledge and driving skills. Rosato has a background in engineering that he supplemented with automotive research. "They are basically fluids that you pour into the gas tank that dissolve the buildups."

When fuel passes through the injectors, the fuel injection system cleaner gets rid of any leftover gunk that's formed. "Using a good fuel injector cleaner can solve the buildups, thus restoring your engine to its original condition," Rosato says. "This, in turn, restores fuel economy (miles per gallon) and responsiveness upon acceleration."

Based on expert opinions and customer satisfaction ratings, here are some of today's best fuel injection cleaners, including gasoline fuel injectors and diesel injectors.

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Best fuel injector cleaner overall

Chevron Techron Concentrate Plus Complete Fuel System Cleaner

Chevron

When it comes to fuel injector cleaners, the type of vehicle you drive matters less than the type of engine that powers it. Again, most vehicles in the US have gasoline-powered engines, but some are powered by diesel engines. Older vehicles may use carburetors, which means they won't even have fuel injectors.

What makes the Chevron Techron Concentrate Plus fuel system cleaner so popular (it's the top cleaning product on Amazon) is that it works in all kinds of vehicles -- cars, trucks, motorcycles, SUVs and more to clean the fuel injection system -- so long as they run on gasoline. Chevron makes a different Techron product for diesel engines. Between the cleaner's versatility and its high customer ratings (Amazon users have given it a 4.6 out of 5), it's no wonder that analysts and consumers alike swear by it.

Chevron Techron Concentrate Plus cleaning agent contains polyetheramine, or PEA, an ingredient that aids in cleaning and helps make the product so effective. It allows the cleaner to erode the carbon deposits that build up as a result of normal usage, and thereby help the engine performance (and the vehicle) run more efficiently.

One final note: This product is an entire fuel system cleaner, not just a fuel injector cleaner, which means it's designed to clean out the entirety of your vehicle's fueling system, including your fuel lines, fuel rail and fuel pump. Chevron also sells a Techron Concentrate Plus designed just for fuel injectors, which has less PEA and is less expensive.

Best fuel injector cleaner for diesel engines

Lucas Upper Cylinder Lubricant and Injector Cleaner

Lucas

Many people think diesel engines are reserved for large trucks, but they're popular in passenger cars in Europe and Asia. Diesel engines run differently from gasoline engines, so it's no surprise that they'd need a cleaning product specifically formulated to reduce buildup on their fuel injectors.

Lucas Upper Cylinder Lubricant and Injector Cleaner is just such a cleaning product: It's designed to clean the fuel systems of diesel engines and gasoline engines whether they're fuel injected or carburated, putting it at an elite level of versatility. The fuel additive also lubricates the various components of these fuel systems, including diesel injector and fuel rail, allowing fuel to pass more efficiently -- that means you get more bang for your buck when it's time to fill up, and less sediment will be left behind in the future.

For diesel engines, Lucas Upper Cylinder Lubricant and Injector Cleaner is particularly helpful. According to the manufacturer, it "neutralizes the harmful effects of low-sulfur diesel fuel." This allows the fuel to comply with environmental sulfur regulations without causing some of the associated problems, like seal shrinkage. All this makes it an ideal choice for diesel engines. Lucas offers it in 5.25-ounce, 32-ounce and 1-gallon containers.

Best fuel injector cleaner for high-mileage cars, engines and vehicles

Gumout Regane High Mileage Fuel System Cleaner

Gumout

If your vehicle has accrued a lot of mileage (more than 75,000 miles, say), it's likely that the fuel injectors have accrued a good deal of sedimentary buildup. This is especially true if you've never used fuel injection cleaner, or if you've been using weaker fuel cleaner products.

For high-mileage engines, you'll need a particularly strong fuel system cleaner, and Gumout's Regane High Mileage formula cleaning agent fits the bill. It contains PEA, which helps erode the deposits that form on fuel injectors after repeated usage. And, according to Gumout, the cleaner "reduces friction in the upper cylinder to improve fuel economy." It also works to prevent future carbon buildup after usage and improve engine performance.

Customers on Amazon have made their satisfaction with the Gumout Regane High Mileage Fuel System Cleaner quite clear. The product has a 4.6-star rating out of a possible five and 84 positive reviews touting everything from its cleaning efficacy to its temperature versatility. You can purchase Gumout's high-mileage cleaner individually or spring for a six-pack.

Best fuel injector cleaner for direct-injection cars and engines

Royal Purple Max Atomizer Fuel Injector Cleaner

Royal Purple

Direct-injected engines differ from standard, or manifold-injected, engines by squirting gasoline directly into the engine's combustion chamber rather than spraying it in the intake tract. Direct-injection engines are touted for providing better performance and fuel efficiency, and they have become increasingly prominent over the past decade.

Since direct-injected engines function differently, it's no surprise that they collect buildup differently and need to be treated differently. Royal Purple Max Atomizer Fuel Injector Cleaner is specifically designed to treat these engines' fuel injectors. It also maximizes horsepower and won't cause any damage to emissions systems. That said, the cleaner can be used on any gasoline or diesel engines, making it one of the more versatile fuel injector cleaners on the market.

One of the things that makes the cleaner so effective is that it contains the PEA necessary to give your fuel injectors the most complete cleaning to help improve engine performance -- provided you use it often enough. Royal Purple recommends adding a bottle of the Max Atomizer Fuel Injector Cleaner to your gas tank every time you fill it up, but suggests using a bottle every 3,000 miles at the bare minimum. If you do take Royal Purple's advice and use one at every fill-up, it's available in packs of 10 at a healthy discount.

Best fuel injector cleaner for Hemi engines

Amsoil P.i. Performance Improver

AMSOIL

Introduced for automobiles 70 years ago, Chrysler's Hemi engine is a gasoline-burning powerplant named after the hemispherical shape of the combustion chambers. Hemis are considered high-performing engines and can typically be found in muscle cars and pickup trucks, but they are also thought of as less efficient and environmentally sound than regular engines.

Many drivers of Hemi vehicles recommend the Amsoil P.i. Performance Improver, a cleaner for your car's entire fuel system. While it's not geared toward Hemi engines specifically -- Amsoil P.i. will work with any gasoline direct-injection, or GDI, engine -- the benefits the cleaner offers may be particularly attractive to those with Hemi engines in their cars.

By cleaning deposits as effectively as it does (Amsoil's site says "testing shows P.i. restored GDI fuel injectors to a 100% flow rate after one tank of fuel"), Amsoil P.i. gives Hemi engines quite the helping hand. It reduces emissions such as hydrocarbons, carbon monoxide and oxides of nitrogen, and improves fuel economy, addressing two major concerns when it comes to Hemis.

Comparison of best fuel injector cleaners

	Brand	Name	Size	Price
Best overall fuel injector cleaner	Chevron	Techron Concentrate Plus Complete Fuel System Cleaner	12 ounces	$4.94
Best fuel injector cleaner for diesel engines	Lucas	Upper Cylinder Lubricant and Injector Cleaner	5.25 ounces, 32 ounces, 1 gallon	$3.97, $9.99, $26
Best fuel injector cleaner for high-mileage cars/engines/vehicles	Gumout	Regane High Mileage Fuel System Cleaner	6 ounces	$4.44
Best fuel injector cleaner for direct-injection cars/engines	Royal Purple	Max Atomizer Fuel Injector Cleaner	6 ounces	$5.99
Best fuel injector cleaner for Hemi engines	Amsoil	P.i. Performance Improver	12 ounces	$14.49

For the best results, Royal Purple says you should use a bottle of Max Atomizer Fuel Injector Cleaner at every fill-up.

Jon Wong/Roadshow

What you need to know about cleaning your fuel injectors

While there is a difference between fuel system cleaners and fuel injector cleaners, the former can typically be used in place of the latter. In fact, many drivers prefer to use full fuel system cleaners, as they're often stronger than cleaners designed specifically for fuel injectors. Fuel injector cleaners, on the other hand, are typically a bit cheaper than their full-system counterparts.

There are a few ways to tell if it's time to clean your fuel injectors. Your car's gas mileage may dip, and may have a rough idle or decreased throttle response due to dirty injectors. Your engine may stall or have difficulty starting. As far as how long it will take to fix those problems, it really depends on your fuel injector cleaning product. Higher-quality cleaning-fluid products will lead to improvement after fewer applications than others -- you may even see improvement after running through just a single tank of fuel. A severely clogged fuel injector may need to be sent to a cleaning service for ultrasonic cleaning before your engine can return to proper working order.

If your car is running rough and returning decreased fuel economy, one of these fuel injector cleaners may help.

Jon Wong/Roadshow

You also don't need to wait until you have a problem before you decide to clean your fuel injectors -- regular maintenance can save you the trouble of a poor-performing vehicle. By using a cleaner every 1,550 miles on a gasoline engine (or with every tank for a diesel engine), you can get rid of sediment buildup before it reaches a noticeable level, and avoid the symptoms associated with clogged injectors. You should note, however, that using a cleaner every 1,550 miles is simply a rule of thumb, and many products have their own specific instructions associated with frequency of use for optimal fuel-injection cleaning.

Fuel injector cleaners are just one kind of fuel additive, or product that can be added to your fuel to affect your vehicle's performance and overall condition. There are other additives that affect the fuel itself. For instance, a fuel stabilizer can be added to a car that won't be used for a long period of time in order to preserve the gas and prevent it from causing damage to the engine.

There's no harm in adding fuel injector cleaner and fuel stabilizer to the same gas tank. "Most fuel injector [or] system cleaners actually double up as fuel stabilizers: They preserve and clean the fuel so that it doesn't go bad after some time without using it," says Rosato. "These cleaners are actually recommended if you plan on leaving your car parked for a long period of time."

Lucas Upper Cylinder Lubricant and Injector Cleaner is available in 5.25-ounce, 10-ounce and 1-gallon bottles.

Jon Wong/Roadshow

Even if a fuel injector cleaner isn't also a fuel stabilizer, it's still OK to leave it in your tank for extended periods of time. "Generally speaking, however, even if you use a particularly strong cleaner, you just pour it into the fuel reservoir," says Rosato. "If you don't use your vehicle the cleaner is just going to stay there in the reservoir and do nothing 'actively.' So, unless you're pouring lava into the reservoir, you can just relax. The worst that could happen is that the cleaner goes stale and becomes useless after quite some time. Nothing to be worried about."

Some consumers also express concern about whether or not fuel injector cleaners can be used in turbocharged or supercharged car engines. "The simplest and safest answer is to look up what the manufacturer of the vehicle recommends," says John Burkhauser, director of education at Bolt On Technology and an auto repair specialist with over 35 years of experience. He has been published in the US and Europe. "My opinion is using these additives properly for normal street driving is acceptable."

Finally, when it comes to selecting the best fuel injector cleaner, your vehicle type will affect your choice, but certain features are universally helpful -- namely, the presence of PEA and the shape of the container. PEA is especially effective when it comes to dissolving sediment and cleaning engines, and its presence should be a priority in your selection. (Many reputable cleaner brands will make their products' ingredients public via safety data sheets.) Additionally, some containers have spouts and are measured to exact application amounts, making pouring easier.

Chevron offers a full lineup of fuel additives for a variety of applications.

Chevron

Five things to know before using fuel injector cleaner on your vehicle

Are you experiencing vehicle performance or fuel consumption issues? If so, you may have dirty fuel injectors and it might be time for a cleaning. Even if you aren't, you should consider using fuel injector cleaner every set number of miles -- 1,550, or whatever amount is recommended by the cleaner manufacturer.
How severe are the problems you're experiencing? If they greatly impact your driving -- or if you don't see any improvement after fuel injector cleaner treatment -- you may need to skip straight to ultrasonic cleaning.
What kind of engine does your vehicle have? Most have gasoline engines, but diesel engines also represent a significant percentage of vehicles on the road. You'll need to get a cleaning product specifically designed for your type of engine.
Do you want a fuel system cleaner or a fuel injector cleaner? Again, fuel system cleaners are typically stronger since they need to clean all parts of the system, but fuel injector cleaners are usually cheaper.
Does the cleaner you're considering contain polyetheramine? PEA is an ingredient that makes fuel system and injector cleaners more effective, and many drivers won't consider a fuel cleaner product that doesn't have it.

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Written by Scott Fried for Roadshow.

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