There comes a time of year when you need to store your boat. When doing this, people usually leave their fuel tanks full instead of draining them. This is completely fine, as long as you add a fuel stabilizer to the mix. Fuel suffers structural changes over time, and stale fuel can be useless for burning, while the varnish-like residue can cause clogging and damage your motor.

You should use a stabilizer because there are many benefits, and no harm is done to the motor. It will prevent chemical reactions in the fuel, and also clean the system so your motor becomes more efficient. This also means less maintenance which is an additional plus. You can add a dose of stabilizer even for daily use, but it’s a must if you plan to store the motor for months until next use.

Even though the purpose is pretty straightforward, not all products are the same. To find the best boat fuel stabilizer you need to consider several things. Since their content and concentration are not the same, you need to pick out one which performs best in your particular circumstances.

It also needs to be reliable, and we’ve picked out great stabilizers which have been tested and proven their value. Be sure to look at our buying guide to learn more about fuel itself, stabilizers, and also why it’s highly recommended that you add them.

How To Choose A Boat Fuel Stabilizer – Buying Guide


Whether you’re using the boat regularly and need stabilizer for cleansing purposes, or you’re preparing to put on the boat cover and store it, you need an efficient product. You want the engine to start right away when you take the boat out on the water again.


As we mentioned, many people like to leave their tanks full when storing. This is to reduce oxygen levels present in the tank, and prevent possible corrosion problems which may occur as a consequence. However, this too can be problematic, especially with ethanol fuels. If you choose to leave fuel in the tank (during winter for example), you need to add a stabilizer.

When it comes to dosage, this depends on the manufacturer and concentration of stabilization. It’s usually stated on the label which amount you should add. Generally you need more stabilizer added if you’re preparing it for storage than when you’re adding it for everyday purposes when you’re just keeping the system clean.

To get the full benefit, run the motor for a few minutes after you’ve added the stabilizer. You’ll be giving it a chance to spread through the system and create complete protection. This way you can have a fully working engine when it’s time to use it again.

You might also like: Top Boat Fuel Tanks


Some fuels have ethanol added to them. This is done because it absorbs a certain part of carbon emissions so it’s safer for the environment, and helps reduce pollution. If you take E15 fuel for example, it has 15% of ethanol and 85% of regular unleaded gasoline in the mix. This can also be a problem, especially for engines which were not designed for ethanol blends.

Ethanol reacts with water, or to be more particular, with oxygen in the water. While oxygen is always present in the tank, having water makes this process much quicker. Moisture always finds its way in, and outside conditions contribute too, for example temperature changes. Higher temperatures will accelerate the process of fuel going bad.

It will absorb around 500ppm (parts per million) of water, before phase separation happens. This is a chain reaction which results in a particles separating from the fuel. Because they are heavier, they fall to the bottom of the tank and form a sludgy layer.

If this gets pulled into the system, it will cause corrosion and damage. On the other hand, diesel fuel will grow algae when stored untreated for too long. This can have the same damaging effect on your motor, leading to expensive repairs.

Evaporation and oxidation are processes which will inevitably happen to any fuel. However, a stabilizer will react with water before the fuel does, and prevent the chain reaction we mentioned. Be aware that this isn’t something that can last forever, it can only prolong fuel life. If you don’t burn it during that time period, you’ll need to replace it with fresh fuel to avoid risk to the motor.


Some ingredients are added to the stabilizer which help clean and lubricate the fuel system, in addition to preventing phase separation. It goes through the system, and protects it from corrosion. It also cleans it in the process, removing excess gunk and improving burning efficiency. However, if phase separation does happen, you will have to drain your tank, there is no way around it.


We mentioned that the stabilizer prevents fuel from reacting with water. For this to be successful, you need to apply a pre-determined dose of the product, recommended by the manufacturer. Going overboard with the amount usually won’t do any harm to the motor, but it’s unnecessary. The results will be the same as if you used the recommended dose. You won’t make fuel fresh for longer if you use more. For this reason, adding too much is only wasting the extra stabilizer which you could use with another fuel batch, and it’s also a waste of your money.


Q: What Is A Boat Fuel Stabilizer?


It’s an additive which is used to stabilize fuel and make it usable for a longer period. Fuel is very volatile, and this evaporation process begins as soon as you pour it into your tank. Some fuels contain the mentioned ethanol which is responsible for phase separation. All this contributes to fuel going stale and your engine not starting when you need it to. Adding the best fuel stabilizer to the mix prevents these problems, and saves you from unnecessary headaches.

Q: Why Do I Need A Fuel Stabilizer?


Draining your tank is not a very pleasant experience. People leave a certain amount of fuel in the tank, and more is usually better. As we mentioned above, chemical reactions take place and fuel goes bad and becomes unusable. A stabilizer will prolong its freshness, making it good for up to two or more years instead of only a couple of months when untreated.

Q: Can A Fuel Stabilizer Reverse Bad Fuel?


If the fuel has already gone bad and phase separation took place, there is nothing the fuel stabilizer can do – it can’t reverse the reaction. You need to replace it with fresh one. Stabilizers are added to prevent damage (before it happens), so you should add it right away, as soon as you pour fresh gas into the tank.

Q: How Can I Be Sure That A Fuel Stabilizer Is Not Snake oil?


A number of manufacturers aren’t very honest about their products, and claim they have some magical properties. You want something that will work when you add it and avoid being unpleasantly surprised come spring time, when you try to start your motor and it fails.

Some products and manufacturers have been around for a long time, and they have made a name for themselves. This is because their products do what they’re supposed to, and don’t overpromise. Be sure to check the user experience, and learn more about a certain stabilizer and what you can expect from it.

Don’t trust products which make unreasonable claims, stabilizers are very good but won’t double the performance of your engine for 30% less fuel. Also, in order for it to work, there needs to be a substantial amount of stabilizer present in the tank. A product that claims that one droplet can stabilize a full gas tank isn’t telling the truth.

Q: How Do Fuel Stabilizers Work?


The ingredients present in stabilizers stop the fuel from reacting with water and prevent phase separation. Stabilizers are anti-oxidants which absorb oxygen before fuel does, and slow down the negative effects of fuel storage.

Globo Surf Overview

Buying a quality fuel stabilizer is a very inexpensive way to save the fuel during storage, whether it’s in the boat tank, storage tank or any other place. Like discussed, it preserves your motor too, thanks to the extra ingredients which do the cleaning and lubricating. It’s also a time saver, because it’s nice to be able to start the motor immediately and spend more time enjoying fishing and other water activities. You have every reason to start using it right away, we are sure you won’t regret it.

More Boating Parts Reviews:

 Boat Switch Panels