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LAST UPDATED: January 31, 2020

Best Fuel Additives: Maximize Your Fuel Efficiency with These Top Picks

These fuel additives are among the best and perform well in all gasoline vehicles

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PUBLISHED ON January 31, 2020

Even though your vehicle needs gasoline, fuel can leave deposits that can damage your vehicle’s system. Fuel additives will not only maximize fuel efficiency but also prevent and fix many problems. If you want to avoid rough idling, stumbling, weak acceleration, and stalling, then you should consider getting a fuel additive for your vehicle. To help you make an informed choice, here are some of the best fuel additives available on the market today.

  • Best Overall
    LUCAS LUC10013 Fuel Treatment
    LUCAS LUC10013 Fuel Treatment
    Summary
    Summary

    This fuel additive is formulated for both gas and diesel engines. It features strong compounds that clean and lubricates the fuel system for maximum performance. It has a blend of additives that gives the fuel system maximum efficiency.

    Pros
    Pros

    It can be used in vehicles that require leaded fuel because it substitutes the benefits of lead in gasoline. It also increases the lifespan of injectors and pumps. What’s more, it increases the power of your vehicle by burning excess exhaust emissions.

    Cons
    Cons

    It contains chemicals that can be harmful to the environment. Slight contact with this additive causes skin irritation.

  • Best Overall
    LUCAS LUC10013 Fuel Treatment
    LUCAS LUC10013 Fuel Treatment
  • Best Value
    Red Line Complete Fuel System Cleaner
    Red Line Complete Fuel System Cleaner
    Summary
    Summary
    This fuel system additive is designed to clean and prevent corrosion in gas engines. In most cases, it contributes to 100 percent fuel system efficiency after the first clean.
    Pros
    Pros
    Prevents the buildup of gum, carbon, and varnish in the fuel system. Treats all forms of fuel injection systems and promotes fuel stability. Safe for continuous use. Reduces the need for high octane gas.


    Cons
    Cons

    It comes in a small size that may not be enough to treat a large engine system. Not suitable for diesel fuel.

  • Best Value
    Red Line Complete Fuel System Cleaner
    Red Line Complete Fuel System Cleaner
  • Honorable Mention
    Star Tron Enzyme Fuel Treatment Concentrate
    Star Tron Enzyme Fuel Treatment Concentrate
    Summary
    Summary
    This additive is multifunctional and uses unique enzyme technology to enhance fuel efficiency. It features a universal formulation that can be used with any engine or any fuel. Also, it perfectly cleans the fuel delivery system, which aids in fuel economy. 
    Pros
    Pros
    This additive cures and prevents ethanol fuel problems for better engine performance. It stabilizes gasoline for up to two years. This chemical is not harmful to your system in case of an overdose.


    Cons
    Cons

    Its bottle does not allow for spill-free pouring. It is also the most expensive on this list.

  • Honorable Mention
    Star Tron Enzyme Fuel Treatment Concentrate
    Star Tron Enzyme Fuel Treatment Concentrate

    Even though your vehicle needs gasoline, fuel can leave deposits that can damage your vehicle’s system. Fuel additives will not only maximize fuel efficiency but also prevent and fix many problems. If you want to avoid rough idling, stumbling, weak acceleration, and stalling, then you should consider getting a fuel additive for your vehicle. To help you make an informed choice, here are some of the best fuel additives available on the market today.

    Best Fuel Additives Reviews & Recommendations 2020

    Best Overall

    Lucas offers a fuel treatment additive that cleans, lubricates, and neutralizes poor quality fuel. It doesn’t contain alcohol or solvents and is made of heat-resistant oils to maintain its effectiveness during extreme pressure conditions in the engine. As for the formulation, the engine oil features fuel injector cleaners that remove sediments and sludge, which often lead to spark plug misfires. It also contains fuel conditioners that neutralize low sulfur problems in the fuel system. 


    This Lucas Fuel Treatment is one versatile product that works on both gas and diesel engines and is known to improve the octane rating of gas. It can also be used on both fuel-injected and carburetor engines and works well on locomotives, marine, and non-road engines. Since the product keeps your fuel system clean and lubricated, you can expect better fuel economy, lowered emissions, and less wear on the critical engine components. 


    Unfortunately, the product has a strong formulation with some chemicals that are considered to be harmful to the environment. You should remember to wear gloves when handling it, as even slight contact can cause skin irritation. It can also stain parts of your car’s paint body with accidental spills. We recommend that you use it with a funnel to avoid spills. 

    Best Value

    This fuel system cleaner offers an alternative to buying high octane gas. This is because it has a patented formula that removes carbon deposits from the engine. It also does a good job of cleaning deposits such as gum and varnish from the carburetors, injectors, valve, and combustion chamber. What’s more, the fluid features a concentrated blend of high- and low-temperature detergents to make it stable and effective under extreme engine conditions. 


    Not only is it a good cleaner, but it also contains a synthetic lubricant that will reduce friction in the upper cylinder. There are no harmful ingredients in the formulation and it, therefore, won’t be toxic for your engine or the environment if used continuously. Lastly, the fluid comes in a clear bottle that’s easy to use, even without a funnel. 


    The main downside of this cleaner is that it comes in a small bottle and you have to keep buying more if you want to reduce the deposits in your fuel system. You may also have to use more than one bottle if you have a large fuel tank. It’s only formulated for gas engines and, therefore, not all vehicles and heavy-duty equipment can benefit from it. 

    Honorable Mention

    The Star Tron Fuel Treatment is a strong fuel system additive that stabilizes gas (including ethanol blends) for up to two years. It has antioxidants that prevent fuel separation. A unique blend of enzymes in its formulation help to improve fuel combustibility and, in turn, provides more engine power and improves fuel economy, even if the engine was sitting idle throughout a season. 


    The product also features deep cleaning action that removes gum, carbon, and varnish from the tanks to the injectors. This eventually makes your engine start easily and run smoothly. It goes further to breakdown excess water and sludge to smaller particles that can be burned away when the engine is in operation. 


    The main drawback of the product is that it’s only suitable for gasoline engines. You need a funnel to pour out the contents since the container doesn’t allow for spill-free pouring. Moreover, it’s a bit expensive in comparison to most one-gallon fuel additives.

    Honorable Mention

    This fuel additive from Hot Shot’s Secret is designed to help diesel engines perform better. It promises to boost cetane by up to seven points, which helps engines start more quickly, especially on cold days. Just 2 ounces makes 25 gallons of diesel fuel a lot more stable, reducing the chance of corrosive deposits.


    Everyday Diesel Treatment is especially useful for diesel vehicles that sit for long periods of time, such as motorcoaches. It keeps the fuel in the tank stable, saving your RV from having to burn layers of soot from its engine when you start it up in the spring.


    EDT is also an effective treatment for the decline in fuel economy that all diesel engines experience at high mileage. Much of that drop in performance is rooted in the deposits that build up in the engine over time—cleaning them out with an additive like this helps them run close to new.


    Be warned that EDT isn’t guaranteed to affect fuel economy in every vehicle and that you might not notice a change. It’s also sensitive to open air, and can turn into impenetrable gunk if left out for too long (and the smell is quite intense).

    Honorable Mention

    Stanadyne Performance Formula is for diesel engines. The company claims that this formula has been proven by independent testing to improve gas mileage by an average of 4 percent, with 9.6 percent as the best gain. We weren’t able to get numbers that rigorous, but we did see noticeably better fuel economy.


    In addition to bumping up your miles per gallon, Stanadyne Performance vows to improve cetane for easier ignition, cut down on your engine’s emissions, and increase horsepower by freeing your engine from soot, gunk, and oxidation.


    That’s a lot of bold statements. Like with any additive, the actual results will vary from vehicle to vehicle. We can say for certain, however, that Stanadyne vastly extends the lifespan of engines and fuel injectors, and makes diesel vehicles run cleaner and quieter. Perhaps the biggest draw, though, is that each bottle is a complete solution, removing the need to buy separate winterizers and stabilizers.


    It’s not perfect, of course. You can only buy bottles in bulk, which will be prohibitively expensive for some. It’s also known to void the warranties on certain vehicles, so make sure to read the terms of your warranty closely if you plan to use it.

    Honorable Mention

    Archoil AR6200 is a treatment for all gasoline and diesel engines. The biggest thing that distinguishes this additive from the crowd is how concentrated it is: ¼ ounce treats a 20-gallon tank. Since the treatment only needs to be added every time you fill up, a single bottle will easily last you for months.


    In that ¼ ounce, Archoil has packed a lubricant, detergent, stabilizer, demulsifier, combustion booster, and rust inhibitor. In gasoline-powered vehicles, it silences knocks and prevents pre-ignition, and helps them sit through off-seasons with their engines unharmed.


    It’s even more effective in diesel vehicles, where it cleans soot out of the engine and the particulate filter. Archoil encourages diesel engines to burn gas more completely, which cuts down on emissions and increases fuel efficiency in a single stroke. It’s also great for the oil in both kinds of engines, helping it come out cleaner.


    All that said, there are some downsides, mostly related to quality control. The occasional bad batch slips through and causes some diesel engines to belch smoke. The other problem is that extreme concentration means AR6200 takes longer to show results than some additives. At first, it might look like nothing has changed.

    Honorable Mention

    Royal Purple Max-Clean is a synthetic fuel additive for the true optimizers out there. Just add it to your tank one time, and it will work its way into your fuel system and start mercilessly cleaning everything it can reach.


    Max-Clean is designed to get into all the crevices. By clearing gunk out of your fuel system, it promises to increase fuel economy, cut emissions, prevent rough idling, and get your horsepower back to new-car levels. It’s also very convenient: You only need to add it every six months or 10,000 miles.


    But does it work? Hopefully, it’s clear by now that it won’t work for everybody. Royal Purple’s tests found that Max-Clean increased fuel efficiency by 3.2 percent and horsepower by 2.6 percent on average. We don’t advocate believing everything companies say about their products, but it’s enough to prove this definitely isn’t snake oil.


    We do have some words of caution: If you have a vehicle with more than 80,000 miles on it and have never cleaned the engine, do it first before using Max-Clean, or risk blowing out your plugs. Additionally, it doesn’t come with a nozzle, which makes it a hassle to actually get into your engine.

    Honorable Mention

    At this point in the list, STP Gas Treatment is stepping into a crowded field. What does it have to differentiate itself? For one thing, the bottle is very user-friendly. One bottle equals one treatment, and the neck is thin enough to fit into your gas tank.


    For another, it’s more interested in water removal than a lot of other additives. If your home gets frigid winters, this is one of our favorite additives for demulsifying and removing water to keep fuel lines from freezing. It’s also an effective detergent. STP can improve performance in old engines that might be suffering from carbon deposits. It helps gas last longer, and is good at stabilizing it in seasonal vehicles.


    There are some bad claims as well. STP says that it contains “jet fuel,” which is not what you might think it is (that is to say, fuel for jets). Instead, it’s an inactive ingredient in STP that takes advantage of “jet fuel” not being a copyrighted phrase. Other than the misleading label, the biggest downside of STP is that the bottles sometimes leak while in transit.

    Honorable Mention

    Quicksilver Quickleen is a well-regarded fuel additive that you might have heard of under its other brand name, Mercury. While it was originally formulated for Yamaha outboard motors, it works in all 2-stroke and 4-stroke gasoline engines (though it’s not for diesel).


    Quickleen scrubs your engine of harmful deposits to improve efficiency, cut down on knocking, and prevent pre-ignitions that can ruin your spark plugs. It’s by far most effective on older engines that haven’t been regularly maintained. These tend to have the most carbon and oxide deposits gumming up the works, and so will see a major performance boost from a decent cleaning.


    It also keeps gas stable, which is to be expected since it was designed for seasonally-used boats. If you have any vehicle or appliance with a gas engine, from a lawnmower to an F-150, Quickleen is a cheap insurance policy for leaving it unused over the off-season.


    The other side of the coin is that if your vehicle isn’t that old, or your engine isn’t that dirty, you likely won’t see much difference from using Quickleen. Shipment is also problematic, with the flimsy glass bottles sometimes arriving broken.

    Why Trust Us


    All of our reviews are based on market research, expert input, or practical experience with most products we include. This way, we offer genuine, accurate guides to help you find the best picks.

    Learn more

    Benefits of Fuel Additives 

    • Improve engine performance. Removing deposits in fuel results in a better flow of the fluid in the engine system. That means that your engine will experience less wear and perform to its full potential while retaining the same amount of fuel consumption.
    • Maintain the quality of fuel you use. Fuel typically starts to break down when it passes through the different parts of the fuel system. The breakdown causes the fuel to degrade, which in turn results in the formation of corrosive deposits such as gum, varnish, and carbon that block the intake valves and carburetor jets. Using a fuel additive can stabilize the fuel and prevent premature degradation. 
    • Prevent breakdowns. The best fuel additives have corrosion inhibitors that reduce wear and premature breakdown of metal parts. This will help you keep your engine in good shape even without frequent maintenance checks. 
    • Reduce carbon emissions. Most fuel additives can remove carbon deposits in the fuel, which equates to better combustion of the fuel and fewer carbon emissions into the environment.

    Types of Fuel Additives

    Gas Treatments

    Gas treatments are formulated with polyisobutene, and for that reason are cheap and widely available. They help improve the quality of gas by getting rid of harmful carbon deposits for cleaner emissions and breaking down water particles that can dilute the fuel. 

    Fuel Injector Cleaner 

    Fuel injector cleaners are an upgrade from gas treatments since they contain polyetheramine (PEA), which is one of the strongest cleaning agents. It also cleans more parts in comparison including the direct fuel injectors. The compound also removes clogs and carbon buildup in the fuel filter to restore it to its full functioning level. 

    Fuel Stabilizer 

    You can expect the quality of fuel to diminish over time if your vehicle is left idle for a season or if the fuel is in storage. Fuel stabilizers work to maintain the quality of the fuel by absorbing water and slowing down oxidation and chemical breakdown of the fuel. It also keeps fuel fresh for a relatively long time if it's in storage. 

    Octane Booster 

    While octane boosters aren’t formulated with the strongest cleaning agents, they do a good job of increasing the octane level in the fuel. Octane boosters help to clear away carbon deposits from the fuel intake system and are typically added to the gas tank before filling it up. A higher octane level results in fewer emissions of greenhouse gases. 

    Top Brands

    Red Line 

    Red Line is a California-based company that was founded in 1979. It currently manufactures more than 100 high-quality car care products. It uses cutting edge technology to create products that meet the performance demands of the industry. Some of its top products include the Red Line Complete Fuel System Cleaner and the Red Line V-Twin Primary Case Oil

    Royal Purple 

    Royal Purple is a Texas-based producer of synthetic oils and lubricants with more than 200 years of experience. Its high-performance synthetic products significantly outperform mineral-based oils, petroleum byproducts, and other synthetics in the industry. Some of its top-quality products include the Royal Purple Max-Clean and the Royal Purple 10-48.

    Chevron 

    Chevron manufactures a wide line of additives that improve the performance of lubricants and fuels. Its products can be used on a wide line of vehicles, motorcycles, ships, farms, and industrial equipment. The company was founded in 1984 and has different brands under its umbrella including Techron, Caltex, Star Mart, Revtex, and Delo. Some of its best-rated oil additives include the Chevron Techron Concentrate Plus Fuel System Cleaner and the Techron D Concentrate

    Lucas 

    Lucas is one of the best North American-based manufacturers of lubricants, fuel additives, and automotive oils. The company was founded in 1989 and is currently headquartered in Corona, California. It’s also a sponsor of the American racing industry. Some of its popular products include the Lucas Transmission Fix and the Lucas LUC10013 Fuel Treatment

    Fuel Additives Pricing

    • Under $30: The pricing difference with fuel additives is usually determined by the size of the bottle. You should, therefore, expect to find anything below a gallon within this price range. How good or effective it depends on the brand and formulation.
    • Over $30: Expect to find anything above a gallon in this price range. You will need to purchase an extra funnel, preferably a calibrated one, to measure the contents that you pour into the system, and to avoid making a mess. 

    Key Features

    Engine Compatibility 

    Some manufacturers make fuel additives that are specific to either diesel or gas engines. You can also find a multifunctional product that works for both. It’s important that you choose a product that’s compatible with your engine’s fuel to avoid corrosive chemical reactions and damage rubber seals that will result in engine failure. Also, consult your owner’s manual on what types of formulations or ingredients you should avoid for your engine. 

    Amount 

    Fuel additives come in different sizes from 11-ounce bottles to large 5-gallon jars. If you don’t like to hoard car care products in your garage, you can go for a small bottle with just the right amount to treat your engine. However, there’s an upside to buying larger quantities: You can treat multiple vehicles or save money in the long run if it comes with a reasonable price tag. 

    EPA Approval 

    Prioritize fuel additives have an EPA (Environmental Protection Agency) label, meaning that they comply with environmental regulations. Such a product typically works by dissolving carbon deposits in the fuel to reduce exhaust smoke production and harmful carbon emissions into the atmosphere. 

    Other Considerations

    • Ease of Use: Ideally, there’s no learning curve to using a fuel additive since most come pre-prepared. What you are looking for, in this case, is a well-packaged, clear container that’s easy to hold and lets you know how much fluid is left.
    • Range of Use: Prioritize additives that offer a wide number of benefits to the fuel system besides cleaning it. The best oil additives lubricate the engine parts, stabilize the fuel, prevent corrosion, and some also have engine cooling agents. 
    • Shelf Life: It’s important to choose a product with a long shelf life if you plan on buying in bulk or using the additive for a long period. Additives can remain stable for at least two years but when they expire, they typically leak from their containers. It’s a no-brainer that it will be useless after that. 

    Best Fuel Additives Reviews & Recommendations 2020

    Best Overall
    Lucas LUC10013 Fuel Treatment

    Lucas offers a fuel treatment additive that cleans, lubricates, and neutralizes poor quality fuel. It doesn’t contain alcohol or solvents and is made of heat-resistant oils to maintain its effectiveness during extreme pressure conditions in the engine. As for the formulation, the engine oil features fuel injector cleaners that remove sediments and sludge, which often lead to spark plug misfires. It also contains fuel conditioners that neutralize low sulfur problems in the fuel system. 


    This Lucas Fuel Treatment is one versatile product that works on both gas and diesel engines and is known to improve the octane rating of gas. It can also be used on both fuel-injected and carburetor engines and works well on locomotives, marine, and non-road engines. Since the product keeps your fuel system clean and lubricated, you can expect better fuel economy, lowered emissions, and less wear on the critical engine components. 


    Unfortunately, the product has a strong formulation with some chemicals that are considered to be harmful to the environment. You should remember to wear gloves when handling it, as even slight contact can cause skin irritation. It can also stain parts of your car’s paint body with accidental spills. We recommend that you use it with a funnel to avoid spills. 

    Best Value
    Red Line Complete Fuel System Cleaner

    This fuel system cleaner offers an alternative to buying high octane gas. This is because it has a patented formula that removes carbon deposits from the engine. It also does a good job of cleaning deposits such as gum and varnish from the carburetors, injectors, valve, and combustion chamber. What’s more, the fluid features a concentrated blend of high- and low-temperature detergents to make it stable and effective under extreme engine conditions. 


    Not only is it a good cleaner, but it also contains a synthetic lubricant that will reduce friction in the upper cylinder. There are no harmful ingredients in the formulation and it, therefore, won’t be toxic for your engine or the environment if used continuously. Lastly, the fluid comes in a clear bottle that’s easy to use, even without a funnel. 


    The main downside of this cleaner is that it comes in a small bottle and you have to keep buying more if you want to reduce the deposits in your fuel system. You may also have to use more than one bottle if you have a large fuel tank. It’s only formulated for gas engines and, therefore, not all vehicles and heavy-duty equipment can benefit from it. 

    Honorable Mention
    Star Tron Enzyme Fuel Treatment Concentrate

    The Star Tron Fuel Treatment is a strong fuel system additive that stabilizes gas (including ethanol blends) for up to two years. It has antioxidants that prevent fuel separation. A unique blend of enzymes in its formulation help to improve fuel combustibility and, in turn, provides more engine power and improves fuel economy, even if the engine was sitting idle throughout a season. 


    The product also features deep cleaning action that removes gum, carbon, and varnish from the tanks to the injectors. This eventually makes your engine start easily and run smoothly. It goes further to breakdown excess water and sludge to smaller particles that can be burned away when the engine is in operation. 


    The main drawback of the product is that it’s only suitable for gasoline engines. You need a funnel to pour out the contents since the container doesn’t allow for spill-free pouring. Moreover, it’s a bit expensive in comparison to most one-gallon fuel additives.

    Honorable Mention
    Hot Shot's Secret Everyday Diesel Treatment

    This fuel additive from Hot Shot’s Secret is designed to help diesel engines perform better. It promises to boost cetane by up to seven points, which helps engines start more quickly, especially on cold days. Just 2 ounces makes 25 gallons of diesel fuel a lot more stable, reducing the chance of corrosive deposits.


    Everyday Diesel Treatment is especially useful for diesel vehicles that sit for long periods of time, such as motorcoaches. It keeps the fuel in the tank stable, saving your RV from having to burn layers of soot from its engine when you start it up in the spring.


    EDT is also an effective treatment for the decline in fuel economy that all diesel engines experience at high mileage. Much of that drop in performance is rooted in the deposits that build up in the engine over time—cleaning them out with an additive like this helps them run close to new.


    Be warned that EDT isn’t guaranteed to affect fuel economy in every vehicle and that you might not notice a change. It’s also sensitive to open air, and can turn into impenetrable gunk if left out for too long (and the smell is quite intense).

    Honorable Mention
    Stanadyne Performance Formula Diesel Fuel Additive

    Stanadyne Performance Formula is for diesel engines. The company claims that this formula has been proven by independent testing to improve gas mileage by an average of 4 percent, with 9.6 percent as the best gain. We weren’t able to get numbers that rigorous, but we did see noticeably better fuel economy.


    In addition to bumping up your miles per gallon, Stanadyne Performance vows to improve cetane for easier ignition, cut down on your engine’s emissions, and increase horsepower by freeing your engine from soot, gunk, and oxidation.


    That’s a lot of bold statements. Like with any additive, the actual results will vary from vehicle to vehicle. We can say for certain, however, that Stanadyne vastly extends the lifespan of engines and fuel injectors, and makes diesel vehicles run cleaner and quieter. Perhaps the biggest draw, though, is that each bottle is a complete solution, removing the need to buy separate winterizers and stabilizers.


    It’s not perfect, of course. You can only buy bottles in bulk, which will be prohibitively expensive for some. It’s also known to void the warranties on certain vehicles, so make sure to read the terms of your warranty closely if you plan to use it.

    Honorable Mention
    Archoil AR6200 Fuel Treatment

    Archoil AR6200 is a treatment for all gasoline and diesel engines. The biggest thing that distinguishes this additive from the crowd is how concentrated it is: ¼ ounce treats a 20-gallon tank. Since the treatment only needs to be added every time you fill up, a single bottle will easily last you for months.


    In that ¼ ounce, Archoil has packed a lubricant, detergent, stabilizer, demulsifier, combustion booster, and rust inhibitor. In gasoline-powered vehicles, it silences knocks and prevents pre-ignition, and helps them sit through off-seasons with their engines unharmed.


    It’s even more effective in diesel vehicles, where it cleans soot out of the engine and the particulate filter. Archoil encourages diesel engines to burn gas more completely, which cuts down on emissions and increases fuel efficiency in a single stroke. It’s also great for the oil in both kinds of engines, helping it come out cleaner.


    All that said, there are some downsides, mostly related to quality control. The occasional bad batch slips through and causes some diesel engines to belch smoke. The other problem is that extreme concentration means AR6200 takes longer to show results than some additives. At first, it might look like nothing has changed.

    Honorable Mention
    Royal Purple Max Clean Fuel System Cleaner and Stabilizer

    Royal Purple Max-Clean is a synthetic fuel additive for the true optimizers out there. Just add it to your tank one time, and it will work its way into your fuel system and start mercilessly cleaning everything it can reach.


    Max-Clean is designed to get into all the crevices. By clearing gunk out of your fuel system, it promises to increase fuel economy, cut emissions, prevent rough idling, and get your horsepower back to new-car levels. It’s also very convenient: You only need to add it every six months or 10,000 miles.


    But does it work? Hopefully, it’s clear by now that it won’t work for everybody. Royal Purple’s tests found that Max-Clean increased fuel efficiency by 3.2 percent and horsepower by 2.6 percent on average. We don’t advocate believing everything companies say about their products, but it’s enough to prove this definitely isn’t snake oil.


    We do have some words of caution: If you have a vehicle with more than 80,000 miles on it and have never cleaned the engine, do it first before using Max-Clean, or risk blowing out your plugs. Additionally, it doesn’t come with a nozzle, which makes it a hassle to actually get into your engine.

    Honorable Mention
    STP Gas Treatment

    At this point in the list, STP Gas Treatment is stepping into a crowded field. What does it have to differentiate itself? For one thing, the bottle is very user-friendly. One bottle equals one treatment, and the neck is thin enough to fit into your gas tank.


    For another, it’s more interested in water removal than a lot of other additives. If your home gets frigid winters, this is one of our favorite additives for demulsifying and removing water to keep fuel lines from freezing. It’s also an effective detergent. STP can improve performance in old engines that might be suffering from carbon deposits. It helps gas last longer, and is good at stabilizing it in seasonal vehicles.


    There are some bad claims as well. STP says that it contains “jet fuel,” which is not what you might think it is (that is to say, fuel for jets). Instead, it’s an inactive ingredient in STP that takes advantage of “jet fuel” not being a copyrighted phrase. Other than the misleading label, the biggest downside of STP is that the bottles sometimes leak while in transit.

    Honorable Mention
    Quicksilver Quickleen Engine & Fuel System Cleaner

    Quicksilver Quickleen is a well-regarded fuel additive that you might have heard of under its other brand name, Mercury. While it was originally formulated for Yamaha outboard motors, it works in all 2-stroke and 4-stroke gasoline engines (though it’s not for diesel).


    Quickleen scrubs your engine of harmful deposits to improve efficiency, cut down on knocking, and prevent pre-ignitions that can ruin your spark plugs. It’s by far most effective on older engines that haven’t been regularly maintained. These tend to have the most carbon and oxide deposits gumming up the works, and so will see a major performance boost from a decent cleaning.


    It also keeps gas stable, which is to be expected since it was designed for seasonally-used boats. If you have any vehicle or appliance with a gas engine, from a lawnmower to an F-150, Quickleen is a cheap insurance policy for leaving it unused over the off-season.


    The other side of the coin is that if your vehicle isn’t that old, or your engine isn’t that dirty, you likely won’t see much difference from using Quickleen. Shipment is also problematic, with the flimsy glass bottles sometimes arriving broken.

    Tips

    • When fuel additives come in contact with your skin or eyes, wash them right away. If you swallow the fuel additive, see a physician as soon as possible. 
    • To get the best out of your fuel additive, always use it on an empty tank or just before your next refill. This is because these chemicals work well before combustion. 
    • To ensure that your vehicle’s engine is well-protected, use the right amount of additive and refill as necessary.

    FAQs

    Q: Will fuel additives damage my car?

    A:  Fuel additives are harmless to vehicles. You can rest easy knowing that your vehicle will be safe and perform better. However, you should be careful when using engine cooling system additives that are meant to plug leaks.  

    Q: Do fuel additives increase mileage?

    A: Using additives does not result in an increase in gas mileage. However, this does not make them worthless. They reduce carbon monoxide emissions, remove water in the fuel and get rid of any deposits that can harm your engine. This ensures your vehicle stays safe and your engine stays strong.

    Q: When should I add the additive?

    A: Gas treatments work best when they are added to the fuel tank first, before combustion. This means if you want to add a fuel additive, you should do so before you add any more gas to your vehicle. Just put in the recommended amount even if your tank is not empty.

    Final Thoughts

    We recommend the LUCAS LUC10013 Fuel Treatment because it is the best for taking care of your vehicle and improving its performance.

    For a cheaper yet efficient product, the Red Line Complete Fuel System Cleaner is our recommendation. It will make sure that the fuel system remains clean at all times.