This article contains affiliate links. If you click on these and make a purchase, we may receive a small percentage of the sale without any additional costs to you. Click here to find out more.

6 Best Fuel Stabilizer for Boats – (Reviews & Buying Guide 2021)

Did you know that you don’t have to dump the fuel out of your tank before winterizing your boat? Why waste your fuel and money when there’s something you can do about it. The best fuel stabilizer for boats can do wonders for your vessel and your pocket. Finding the right product for your requirements can help you save money on fuel and repairs.

If the time has come and you have decided to invest in such a magical potion, we are here to help you along the way. Here we have several fuel stabilizers for boats reviews and an entire buying guide.

Keep reading and you’ll learn more about how fuel additives work and what are the benefits of using one for your boat.

Best Fuel Stabilizer for Boats Comparison Chart

STA-BIL Marine Fuel Stabilizer

STA-BIL Marine Fuel Stabilizer

  • Price: $$
  • Size: 32 oz.
  • Treatment: Up To 320 Gallons
  • Suitable For: All Vehicles
View On Amazon
Star Tron Enzyme Fuel Treatment by STAR BRITE

Star Tron Enzyme Fuel Treatment by STAR BRITE

  • Price: $$$$
  • Size: 128 oz.
  • Treatment: 2048 Gallons
  • Suitable For: Turbocharged, supercharged, box-stock, or high-performance engines
View On Amazon
Yamalube Fuel Additive by YAMAHA

Yamalube Fuel Additive by YAMAHA

  • Price: $$
  • Size: 12 oz.
  • Treatment: 120 Gallons
  • Suitable For: All Vehicles
View On Amazon
Fuel Stabilizer by MERCURY

Fuel Stabilizer by MERCURY

  • Price: $
  • Size: 12 oz.
  • Treatment: 60 Gallons
  • Suitable For: All grades of gasoline, plus ethanol blends
View On Amazon
Briggs & Stratton Fuel Treatment

Briggs & Stratton Fuel Treatment

  • Price: $$
  • Size: 16 oz.
  • Treatment: 80 Gallons
  • Suitable For: Smaller gasoline engines
View On Amazon
Fuel Ox Marine by The Fuel Ox

Fuel Ox Marine Treats Fuel

  • Price: $$$
  • Size: 8 oz.
  • Treatment: 80 Gallons
  • Suitable For: Both inboard and outboard motors and two and four-stroke engines
View On Amazon

Best Fuel Stabilizer for Boats (Top Picks)

We didn’t arrange the reviews in a particular order. These are all top-selling products that we decided to try and review for you.

1. STA-BIL Marine Fuel Stabilizer

STA-BIL Marine Fuel StabilizerSTA-BIL Marine Fuel Stabilizer is available in single bottles of 1 gallon, 8, 10, or 32 oz. The product is also available for bulk in packs of 4, 6, or 12 depending on the size. STA-BIL’s products will keep your boat’s fuel from aging for about 12 months. However, this product does not rejuvenate fuel.

With this stabilizer, you can have a piece of mind that all water will disappear from the fuel. Depending on how you use your boat, you may need to add the stabilizer every time you fill the fuel tank. This fuel stabilizer has four years of shelf life and two after opening the bottle.


  • You can use this product when you winterize your boat.
  • This is a new formula, and ten ounces are enough to treat ten gallons of fuel.
  • You may also use this product for your car or motorcycle.
  • This product can be used on non-ethanol fuel.


  • No disadvantages we could find.

2. Star Tron Enzyme Fuel Treatment by STAR BRITE

Star Tron Enzyme Fuel Treatment by STAR BRITEHere we have a multi-functional fuel additive by STAR BRITE, which can be used on all gas-powered engines and even for other fuels. What this additive does is disperse water from the fuel, eliminate and prevent carbon deposits and gunk build-up.

We recommend that you use this product every time you fill the engine. The box also says that the initial dose should be double than the refills. This fuel stabilizer formula is robust, and one fluid ounce treats sixteen gallons of gasoline. What is more, if you get the 128-ounce size that will be enough for over 2,040 gallons of gasoline. The best part of buying the large size is that it doesn’t have a limited shelf life. Star Tron will be fine on the shelf as long as its cap is put on well.


  • You can use Star Tron to rejuvenate any fuel that has been sitting idle for a long time.
  • This product can stabilize gas for up to two years.
  • It is suitable for turbocharged, supercharged, box-stock, or high-performance engines.


  • You need to be careful when pouring as the spout isn’t the best and may cause spillage.

3. Yamalube Fuel Additive by YAMAHA

Yamalube Fuel Additive by YAMAHAThis fuel additive by YAMAHA comes in a 12-ounce bottle, and that means it will be enough for 120 gallons of fuel. The product is highly concentrated and can last you a long time, depending on the usage. Its formula is designed to eliminate deposits from the fuel tank and injectors. Also, to remove impurities from the intake valves and ports.

What this product gets rid of are varnish and carbon deposits, plus it fights corrosive elements. The fuel additive is oil-based and doesn’t have a shelf life and it doesn’t spoil. At first, you may think this product is a bit pricey, but given the potential cost savings in repairs or buying a new engine, it’s more than worth it.


  • The formula has a conditioner, thus, it keeps the inside of your boat safe and sound.
  • You can use this product to treat your other vehicles.


  • We couldn’t find any disadvantages.

4. Fuel Stabilizer by MERCURY

Fuel Stabilizer by MERCURYThe next boat fuel stabilizer is from MERCURY, and it’s suitable to use on two and four-cycle gasoline engines. This product comes in a 12-ounce bottle, and it’s enough to treat about 60 gallons of gasoline. Per instructions, the recommended dose is one ounce per five gallons of fuel.

How it works is by adding the doze before filling the tank. After the gas is added, you need to run the engine for about five or ten minutes to make sure the stabilizer treats all of the fuel. You can also use this product to stabilize fuel up to a year when your boat is in storage.


  • The formula keeps the fuel injectors and carburetor lubricated.
  • This product is suitable for all grades of gasoline, plus ethanol blends.
  • You may use this fuel stabilizer on all your vehicles – boat, car, truck, motorcycle, lawnmower, etc.


  • There aren’t larger sizes of the product.

5. Briggs & Stratton Fuel Treatment

Briggs & Stratton Fuel TreatmentNow, we have a fuel treatment with an advanced formula from Briggs & Stratton. Their product is recommended for smaller gasoline engines, so if you need to treat a large boat fuel tank, it may not be for you. Also, this fuel stabilizer isn’t recommended to be used on cars.

However, this product has one of the longest-lasting effects. So, even though the bottle is only 16 fl. ounces, it is worth the money. Because of the three years of active time, this product is ideal for preparing your boat for long-term storage. With that amount, you can treat up to 80 gallons of fuel.


  • This product gives your fuel and engine three full years of protection.
  • The advanced formula provides triple antioxidant protection for your boat engine.
  • You can use this fuel treatment for two and four-cycle engines.


  • The bottle itself is cheaply made and increases the risk of leakage.

6. Fuel Ox Marine Treats Fuel

Fuel Ox Marine by The Fuel OxThe Fuel Ox’s product can treat gas or diesel, for both inboard and outboard motors. Their fuel stabilizer serves several purposes. One is removing water and other contaminants, such as carbon build-up. The second feature is to enhance the motor’s performance. And the third is lubricating the engine.

This product is available in 3, 8, or 16-ounce bottles. It is also suitable for two and four-stroke engines. The formula provides full protection from general fuel-related problems to the engine, injectors, tanks, etc. What is more, this product lowers the combustion temperature and makes the process safer.

Overall, if you’re looking for a fairly-priced product to keep your boat engine safe, you may try this one.


  • It’s great for winterizing or de-winterizing your boat.
  • The Fuel Ox keeps gas or diesel from degrading for about two years.
  • This is a very concentrated formula, and one ounce treats up to 80 gallons of diesel or gas.


  • None that we could find.

What is a Marine Fuel Stabilizer

This is a special kind of liquid that keeps your fuel and tank fresh. Also, it aids your engine’s performance. A fuel stabilizer prevents the ethanol in the fuel from going stale when you’re not using your boat for a long time. What is more, ethanol also attracts and retains water. That can cause damages to vital parts in your boat’s mechanism. In other words, this product keeps the boat fuel clean and eliminates or prevents the formation of impurities and destructive substances.

Marine fuel stabilizers come in many variants and are suitable for different situations. That’s why you need to know more about them before you make a purchase.

How Does It Work?

Best Fuel Stabilizer for Boats A fuel stabilizer for boats has two main purposes. One is to act as an antioxidant. The second is to absorb water in the tank or help with its safe discharging. Once you add this fuel additive in the tank, you must start the engine and run it for five or ten minutes, so the liquid distributes evenly.

Air and water aid the process of oxidation. Needless to say that your vessel is in contact with both at all times. When the product starts to work, it will stop the oxidation process in your engine. Keep in mind that these are not the same as oxidation removers. You can read our guide on boat oxidation removers and compare the two types of products.

Furthermore, you can use some products as a preventive treatment and for curing an existing fuel problem. Regardless of whether your boat engine already has a problem with the fuel or you’re looking for protection, you need to consider using a fuel stabilizer.

Why Do I Need A Fuel Stabilizer For My Boat?

As we said above, water and air contribute to chemical reactions occurring in your fuel tank, so do heat and light. These reactions do not have a positive impact on your engine. Furthermore, any petroleum fuel, including diesel, gas, and biodiesel, are often affected by these reactions.

Aside from being exposed to such conditions, with time, fuel can also turn dark. The marine fuel stabilizer will stop these processes from starting. It is paramount that you use a stabilizer if your boat runs on ethanol fuel.

Can a Fuel Stabilizer for Boats Reverse Bad Fuel?

If the fuel has gone bad and stayed that way for an extended time, the answer is no. Phase-separated ethanol or darkened fuel cannot be fixed by a stabilizer. Some products, however, can rejuvenate mildly stale fuels. Most of the stabilizers on the market are intended to prevent fuel problems from occurring in the first place. Some formulas can fix common water problems that most fuels have.

So knowing if your boat has a problem already and what it is can help you when choosing the right fuel stabilizer. If your craft needs more maintenance and care, check out our boat accessories page and read about other boat equipment and supplies.

Types of Fuel Stabilizers for Boats

Based on their ingredients and intended usage, there are many types and they aren’t even categorized. However, we will mention the most common types:

  • Alcohol-free products help stop fuel blends separation and breakdown.
  • Long-lasting stabilizers can keep your fuel fine for up to three years.
  • Some formulas can prevent gunk build-up.
  • Other additives are designed to protect more than just the engine, but also the carburetor, injectors, lines, etc.
  • You can find products that disperse water from the tank without affecting the engine or the fuel.
  • There are also stabilizers that you can use on gas and diesel engines.
  • You can use all-purpose fuel additives on different vehicles, including your boat, car, and lawnmower.
  • Additionally, you can find products that can rejuvenate fuel.

Some products are designed to use when preparing your boat for storage. This means that you need to use the product once or twice a year. On the other hand, there are additives intended to use every time you fill the tank with fuel.

There are also many more types you can find on the market. The first thing you have to know, however, is what your boat needs. Does it have stale fuel? Are you looking for an additive to prevent problems? Do you need a product to keep the fuel stable while your boat is in storage?

Answer these questions, and then you will know what type of fuel stabilizer you need.

How to Choose the Best Boat Fuel Stabilizer

Here are the most important things to consider when looking for the best marine fuel stabilizer:

  • Usage. How often you use your vessel is imperative on how often you need to use a fuel stabilizer. It is worth buying a high-quality product if your boat sees regular use. In the long run, using a fuel additive will protect your engine from misfires as well as from oxidation. It will prolong the life of the engine and save you a lot of money on boat repairs or new parts.
  • Storage. If you are looking for a product to keep the fuel in your boat fresh when kept in storage, you should seek a different product. A stabilizer for regular use has a different formula and won’t help for the months in storage. There are fuel stabilizers that keep gasoline fresh for up to three years, and some are good for only six months.
  • Your fuel type. There are products that work well for gas or diesel fuels. Many kinds of fuels contain ethanol, which attracts water, creating problems for the fuel system. A fuel stabilizer can prevent that from happening. So whichever type of fuel your boat uses, you should buy a stabilizer for that type or a universal one.
  • Additional features. Not all products on the market have something extra in their formula. So, you want to get your money’s worth, and you may buy a product that does more than just keep fuel fresh. For example, some additives also lubricate the fuel system.

Benefits of Marine Fuel Stabilizers

Fuel Stabilizer for Boat ReviewsWe couldn’t find or think of the general drawbacks of using such a product, so we are going to list the advantages that we found.

Aside from a fuel stabilizer’s main job – preventing oxidation and keeping your boat engine in top-performance – check out the other benefits:

  • Boosting engine performance: Some products care for entire fuel systems, which increases the engine’s performance. In fact, some brands even claim their products can make engines 5% more economical.
  • Faster engine warm-up due to the previous benefit. Using fuel additive to lubricate the entire fuel system allows your engine to warm-up and work faster even in cold days.
  • It saves you money on fuel: Depending on the product that you use, you may store the fuel for up to three years. Thus, you don’t have to drain the tank before storage or throw away spoiled fuel.

Frequently Asked Questions

What Happens if I Put Too Much Fuel Stabilizer in My Tank?

Nothing bad can happen if you put more than the recommended dose. Some products even explicitly state that the first usage of the product should be a double dose. For example, if the directions say to use one ounce, you should add two the first time you’re using the product.

So, if you’re supposed to put one ounce in one gallon but you add two ounces, that’s okay. Also, we’d like to mention that even though these products have the consistency of engine oil, they cannot be used as a substitution. For example, if your boat has a 4-stroke engine, you need to use oil suitable for a 4-stroke motor.

How to Care and Maintain a Fuel Additive?

Some products do not have a shelf life and are good for many years, as long as you keep them tightly closed and in the recommended environment. You must keep the stabilizer in a dark, dry, and cool area. It shouldn’t be in direct sunlight and should be kept out of reach of children or pets.

How Much Should I Add to the Boat Tank?

To properly use your fuel stabilizer, you should follow the directions on the bottle because they are different for each product. If such information is missing, you need to contact the manufacturer.

More often, the recommended amount is one ounce of the product for every gallon of fuel in the tank. Then, based on how many gallons of gas your tank can fit, you should add the corresponding amount of stabilizer.

Not all formulas are equal, of course. Some are more concentrated than others, and the amount per gallon is different.

Wrap up

We need to wrap this guide up. As we mentioned, the first thing you should do is think about what you want from the best fuel stabilizer for boats and then look for it. You can see from our post that whether you need it for storage or regular use, you need to look at different product types.

Also, we hope that with our fuel stabilizer for boats reviews you won’t have to go through trial and error. It’s our job to test various marine products and share what we’ve discovered about them – their good and the not-so-good sides.

If you like to share your feedback with us, we would greatly appreciate it. You can do so in the comments section. Also, feel free to ask us any questions about our guide. We’d be happy to help.

Come back soon for more marine product reviews and buying guides!

Leave a Comment