Best Fuel Stabilizer for Small Engines

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Best Fuel Stabilizer for Small Engines

Any gas left sitting in your tank for more than 30 days is going to fade in potency and possibly cause harm to your engine.

Necessary compounds will evaporate which might result in varnish or gum in your vehicle’s fuel system. These will not only cause ignition problems but damage components that can be costly to clean or replace.

Planning and using the best fuel stabilizer for small engines ensures that when you next need your vehicle it will start and drive with no problems. Other types of fuel stabilizers help you get the best from your engine when used at every tank fill. They can make even the poorest quality ethanol/gasoline blend feel as if you’re using premium fuel. Your fuel economy could increase and you could see considerably fewer emissions.

10 Best Fuel Stabilizer for Small Engines

Last update on 2021-12-05 at 07:46 / Affiliate links / Images from Amazon Product Advertising API

We have put together a guide of the best available fuel stabilizers to help you find the one that works the best for you.

1. Star Tron Enzyme Fuel Treatment Concentrate

Whether you’re looking to stabilize a tank of fuel that is likely to be in storage for some time, or you want your vehicle to have a smoother start and run more economically every day, then Star Tron has a great product worthy of consideration. This is the best fuel stabilizer for cars. The enzymes in the formulation ‘eat away’ at any carbon deposits, gums, or varnishes within the entire fuel delivery system. This will reduce fuel emissions allowing for a smoother and more fuel-efficient ride.

Valves and injectors will remain clean and able to work at their optimum. If you’re using the stabilizer at each fuel fill-up, you only need 1 fluid ounce per 16 gallons of gas. The container is marked and has an easy pour dispenser. Adding too much is in no way harmful, it’s just a waste of product. If your vehicle is being left in storage, then 1 application will last up to 2 years, ensuring your fuel will remain in the same condition as the day you filled the tank.


  • Increased fuel efficiency
  • Reduced emissions
  • Ideal for every day or engines rarely used
  • Stabilizes fuel for up to 2 years
  • Cleans entire fuel delivery system
  • Available on 8, 16, 32 and 128 fl oz bottles
  • Suits every gas engine, cars, boats, garden tools, etc


  • Measurements could be more obvious on the side of the container

2. STA-BIL 22214 Red Fuel Stabilizer 

If you need to put your vehicle into storage for at least 30 days then using STA-BIL stabilizer is a perfect choice. It will keep a tankful of fuel fresh for up to 2 years, many users state that after even longer periods their engines started the first time. It is safe for all gasoline engines, including ethanol mixes, and means you won’t have to drain the tank once it’s taken out of storage.

Your engine life extends as carburetors and fuel injectors are cleaned, it prevents rusting as it removes moisture. This is one of the best fuel stabilizers for a lawnmower which is simple to use; fill the tank to 95% capacity, which doesn’t allow room for condensation. Add 2 fluid ounces of the liquid per every 5 gallons of fuel and run the engine for 5 minutes. Then you can store the vehicle knowing that the engine will fire up and run as smoothly as it did the day the tank was filled.


  • Keeps fuel in optimum condition for up to 2 years
  • No need to drain the tank after storage
  • Protects against gum, varnish and corrosion, therefore, prolongs engine life
  • Safe for all gas engines, including those with ethanol
  • Very easy to use


  • Only recommended for use with vehicles in storage

3. PRI Fuel Stabilizer For Gasoline

If your vehicle is going to be stored for a period you will need to add a product to stabilize the fuel, otherwise, it will be of such a poor grade that you will need to drain the tank before the car will be fit to drive. Maybe the vehicle has stood for a while and the fuel quality has degraded, if so, adding a small amount of this product could restore and rejuvenate it. Just 1 fluid ounce per gallon each year is enough to keep the fuel at its optimum quality.

If your car is to be stood for a greater period, just retreat annually. It is suitable for E-10 gasoline, 10% ethanol blend, and both 2 and 4 stroke engines. It is also known as the best gas additive for small engines. A user stated that their car that had stood for a few weeks and had developed a misfire, improved within minutes of adding the Pri-G fuel stabilizer, and provided a lovely smooth ride. By preventing harmful deposits from building up, your emissions will be lower and your fuel efficiency will improve.


  • Reduces HC/NOx emissions
  • Perfect for storage, 1 unit per gallon per year is all that is needed
  • Zero alcohol content
  • Ideal for E-10 gas
  • Improves fuel efficiency


  • No measuring device supplied, we found a syringe best

4. Briggs & Stratton 100119 Fuel Treatment Replaces

This fuel stabilizer is from the recognized brand leader, Briggs, and Stratton. This is the best fuel additive for small engines which comes in a smaller quantity as it is highly concentrated. The tiniest amount will stabilize your fuel for 2 years; add another half an ounce per gallon and your fuel will remain fresh for up to 3 years. It is suited to both 2 and 4 cycle gas cylinders designed with the common corrosive ethanol-related problems in mind.

The metal engine components remain safe from harm. The whole fuel delivery system will remain in peak condition; the added detergent cleans as the engine runs. Added to a full tank of fresh gas, this fuel stabilizer is safe for long-term storage too, your fuel will not go stale and your engine should start with ease.


  • Stabilizes fuel for up to 3 years
  • Brand leader
  • Great value for money
  • Cleans and protects the fuel system
  • Small bottle for convenience, super concentrated


  • Offers no benefit to old gas, only fresh

5. Royal Purple Max-Clean Fuel System Cleaner and Stabilizer

Royal Purple makes some big claims here, 3.2% better fuel economy, emission reductions, greater horsepower, and generally improved performance. It is suitable for every type of engine, gasoline, diesel, turbo, and supercharged, new or old will see a significant improvement after just 1 use of this fuel stabilizer. Because it penetrates and cleans so deeply, it helps to reduce engine performance issues by removing harmful deposits.

Each can is sufficient for single use. Almost empty your gas tank and add the can, then top up with 20 gallons of fuel, this will need adjusting accordingly if your tank is smaller or you want to add more fuel. That is all there is to it, drive away and soon notice a marked improvement in the engine performance and the fuel economy. You won’t need to repeat the application until you have clocked another 10,000 miles.


  • Reduces emissions and increases fuel economy
  • Suitable and safe for every engine and fuel type
  • Increased horsepower
  • Prevents rough idling and engine knocking sounds
  • Keeps the fuel system clean and running at optimum


  • Each bottle is for 1 application only, to mix with 20 gallons of fuel
  • If you have a 30-gallon tank you should buy 2 cans but only use 1.5 of them

6. Maxima 89901 Fuel Storage Stabilizer Additive

This fuel stabilizer has dual purposes, not only will it condition your gasoline to keep it fresh but it will fight corrosion within the entire fuel system. Just 1 fluid ounce for every 1-2.5 gallons will ensure your whole system resists the harmful effects of ethanol and moisture.

Varnish and lacquer will not be able to collect and cause further damage. Just running the engine for 5 minutes after application will ensure the stabilizer reaches all parts of the fuel system and will keep everything in optimum condition during storage. Cranking the engine after a long, still period will not be a problem, fuel will remain high quality and components will be in great shape.


  • Contains corrosive inhibitor
  • Prevent varnish and lacquer build-up
  • 1 bottle can treat up to 80 gallons of fuel
  • Zero alcohol
  • Protects against ethanol and moisture damage
  • For use in all engine types


  • Large bottle if only a small amount is required

7. Sta-Bil 22255 Diesel Formula Fuel Stabilizer

Lucas products have been tried and trusted for many years. The brand has earned a reliable name within the automotive industry. This product is ideal for small amounts of fuel that you need to store although it is available in larger quantities too. Each 1 ounce of the solution will treat 1 gallon of fuel and prevent breakdown. It is very simple to use and is suitable for all grades of gasoline in both 2 and 4 stroke engines.

Vehicles can sit for months at a time and will still crank and run smoothly at the first time of asking. Fuel injectors will be kept clean and your engine will literally purr. Some users use it as a stabilizer during the winter when their vehicle sits in storage and as a regular fuel treatment when the sun is out. Their fuel systems run clean, as though premium quality fuel is always used.


  • Fantastic quality and great value for money
  • Easy pour bottle for ease of use
  • Suits all grades of gasoline
  • Best solution to prevent degradation during storage
  • Overseas delivery 


  • This size bottle only treats 8 gallons of fuel

8. STA-BIL 22264 360 Performance with Vapor Technology

A return visit to a STA-BIL product. The red stabilizer we reviewed earlier was ideal for long-term storage whereas this formula is for use with every tank fill up. Other stabilizers will protect the fuel in the tank but this one protects anything above the fuel line too by leaving a coating on all metal parts of the system and combustion chamber.

This incredible Vapor Technology removes water and prevents corrosive and ethanol damage. You will see great results with your fuel economy and notice how much smoother and cleaner the engine is running. No rough idling here! It is a perfect fuel stabilizer for small engines, not just for your car but keeps it handy for your weed whacker, snowmobile and motorcycle too.


  • Unique vapor technology protects above and below the fuel line
  • Cleans daily-use fuel for improved performance, also keeps it fresh in storage
  • Maximizes fuel economy
  • Cleans entire fuel system
  • For use with all gasoline engines, small cars, trucks, and SUVs


  • Small 10 ozs bottle won’t last long if used at every tank fill, larger, more economical sizes available

9. Star Tron Enzyme Fuel Treatment

This super-concentrated formula is multi-functional, it can stabilize stored fuel for up to 2 years, help to rejuvenate old fuel, and treat your everyday use fuel to give you maximum performance. Its unique formulation helps it to break down harmful water into the tiniest of particles to allow them to burn away during regular engine use.

The entire fuel system, injectors, valves, and carburetor will be cleaned allowing for greater fuel efficiency. Engines will have problem-free starts even after months in storage. Although directed at the diesel driver market, StarTron claims that it is safe for all engines and all fuels, even household heater fuel.


  • Everyday use and seasonal storage
  • Stabilizes fuel for up to 2 years
  • Reduced emissions, deposits and increases economy
  • Improves performance as whole fuel system is kept in optimum condition
  • Safe for use in all engines with all fuel types


  • More expensive large container available in smaller bottles)
  • Measurements could be made clearer

10. STP 18410B Ultra 5-in-1 Fuel Stabilizer

Using this STP fuel stabilizer will not only keep any stored gasoline fresh, but it will also deep clean your entire fuel system with its advanced cleaning technology. This will maintain your vehicle’s performance and result in lower emissions and greater mpg. The concentrated ingredients in the solution provide 3x the cleaning power of the highest-grade gas alone, keeping your engine free of performance diminishing carbon deposits, varnishes, and gums.

By using it at every oil change or around every 4000 miles, you are ensuring that your engine remains lubricated and will always run to the best of its capabilities. It works with the most modern types of gas engines and surely must be worth buying if only to maintain your fuel system in peak condition. Just pour into a half-full tank and wait for the magic!


  • Extreme deep cleaning of the entire fuel system
  • Lubricates engine components
  • Compatible with cap-less gas systems
  • Prevents harmful deposits
  • Saves gas, restores the car to optimum performance
  • Stabilizes fuel during storage


  • Only suitable for gas engines

What is a fuel stabilizer?

It is a formula used to keep your fuel fresher for longer. Particularly ideal for seasonally used vehicles, or collector’s cars that rarely get started up. Once treated, the fuel will remain in prime condition until the engine starts again. It is designed to remove the water that is harmful to your fuel system as it causes corrosion. It also keeps the carburetor and fuel injectors clean and running smoothly. Finally, a fuel stabilizer for a small engine will prolong its life, it protects against gum, varnish, and rust.

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When do I use fuel stabilizer?

If you need to store it for any length of time greater than 30 days. It will keep the fuel fresh and protect the fuel system of the vehicle too. It will prevent a hard start and ignition problems from poor quality, degraded fuel. It can also be used as a treatment with each gas tank fill-up. This will help to keep your engine running smoother, longer, and cleaner. It may also give you more mpg!


What is ethanol phase separation?

As the use of blended fuels is on the rise, so is the potential for ethanol phase separation. This occurs when water gets into a tank of gasoline/ethanol mix fuel. The gasoline becomes soaked and the ethanol and water get dragged to the bottom of the tank.

Is this harmful?

Yes. If the ethanol and water mixture is deep enough to find its way into your vehicle via the suction pump it could cause all kinds of problems. Similarly, the gasoline layer without the correct amount of ethanol could cause your engine to knock.

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Can a fuel stabilizer be added to old fuel?

This really depends on just how old and at what stage of degrading the fuel is. If it has already reached phase separation then it’s advisable not to attempt to clean it, even the most wondrous of chemicals would struggle with fuel in the later stages of separation. This could cause engine problems. If your old fuel has darkened in color, it will be forming gum and varnish; a fuel stabilizer with a very high detergent content could help restore the gas. Attempting to run the engine without treating the fuel would just cause harmful deposits to build upon the injectors and carburetor.

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What are gumming and varnishing?

Caused by oxidation. Hydrocarbons in gas alter when they are exposed to oxygen molecules and cause varnish or gum. In older vehicles, the ethanol that is usually blended in with gasoline acts as a solvent. It dissolves old varnish and gum from the gas tank and fuel lines and then these deposits can clog and coat injectors and carburetors, causing them problems.

Is fuel stabilizer for small engines only for use when storing fuels?

No, though if your fuel is going to be stored for longer than 30 days you should always use a stabilizer. It can also be used as part of your maintenance and car care routine. While some formulae are only suited for storage purposes, there are several that can be used at each fill-up. They can enhance performance and prolong life as they keep your fuel system clean and deposit-free. Our guide shows different products for both uses.

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Do I have to use a fuel stabilizer when storing my vehicle?

You don’t have to, but for a relatively small cost, you could be saved a lot of time and expense later. If you completely drain and clean the whole fuel system including all lines, ensure the gas cap is tight and no moisture or air can get in, and then fill up with fresh gas before attempting to crank the engine, then you may be okay. Otherwise, you can spend a few dollars on a bottle of stabilizer, put it in a full tank of fresh fuel, run the engine for a few minutes to make sure the liquid has done a full cycle, and then forget about it for as many months as you need to. It’s a no-brainer if you ask me.

Why is ethanol in our gasoline if it’s bad for our engines?

This is all to do with air pollution and the Clean Air Act, the fact that it produces less carbon monoxide emissions than regular gasoline. Sadly, it has been found that using E10, 10% ethanol mix, you are almost certainly getting 2 or 3 miles less to the gallon.

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