Any petroleum (including diesel) fuel will be affected by water, oxygen, light and heat. A marine engine is affected by al four factors whenever it is in use.
A fuel stabilizer will allow you to store your boat without the ethanol in your gas tank separating and going bad. The ethanol fuels also absorb water from air, which ends up eating away at all your components.
A fuel stabilizer is a good idea for daily use too, depending on what fuel you use in your boat. Read on for our top five fuel stabilizers and why each one works for different situations.
If you’re fueling up your boat at your local gas station you need something that’s going to stop the ethanol from eating through your tank, filters and carburetors. Ethanol absorbs water from the air over time.
That’s where a fuel stabilizer comes in. If you simply search fuel stabilizer on google, you might struggle to find the right options for a boat or marine engine like a jet ski. We’ve reviewed five of the most popular marine stabilizers to make your choice as easy as possible.
Read Next: Our picks for the best marine battery chargers and motors for trolling.
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Boat Fuel Stabilizers (Comparison Table)
Best Budget 
Best Overall
Brand
STA-BIL
PRI
STA-BIL
Star Tron
LUCAS
Model
Gold Eagle 22207
Fuel Stabilizer For Gasoline
22275 Ethanol Treatment
Enzyme Fuel Treatment
Fuel Treatment
Storage
Yes
No
Yes
Yes
No
Ethanol Engine
No
No
Yes
Yes
Yes
Gasoline Engine
Yes
Yes
No
Yes
No
Regular Usage
No
Yes
Yes
Yes
Yes
Best Budget
Brand
STA-BIL
Model
Gold Eagle 22207
Storage
Yes
Ethanol Engine
No
Gasoline Engine
Yes
Regular Usage
No
Brand
PRI
Model
Fuel Stabilizer For Gasoline
Storage
No
Ethanol Engine
No
Gasoline Engine
Yes
Regular Usage
Yes
Best Overall
Brand
STA-BIL
Model
22275 Ethanol Treatment
Storage
Yes
Ethanol Engine
Yes
Gasoline Engine
No
Regular Usage
Yes
Brand
Star Tron
Model
Enzyme Fuel Treatment
Storage
Yes
Ethanol Engine
Yes
Gasoline Engine
Yes
Regular Usage
Yes
Brand
LUCAS
Model
Fuel Treatment
Storage
No
Ethanol Engine
Yes
Gasoline Engine
No
Regular Usage
Yes
Top Marine Fuel Stabilizers
Best Budget Stabilizer: STA-BIL 22207 Gold Eagle Original Concentrated Fuel Stabilizer
STA-BIL is a well-established name in the fuel stabilizer world. This fuel stabilizer is designed with storage in mind, rather than regular usage.
We recommend this fuel stabilizer for when you are planning to store your boat for a month or two while you’re away. If you have a boat that you store in your holiday home, this would work perfectly too.
This storage fuel stabilizer will keep the fuel from going bad, as well as protecting your engine from gumming up or rusting while in storage. This is a must for a boat that’ are used in a marine environment.
STA-BIL, if added to fresh fuel, will keep any gasoline fuel fresh for up to 24 months during storage. We recommend adding the fuel stabilizer to an empty tank and then going to fill up your fuel with gas, as that will help it mix properly.
Be sure to run your engine for a few minutes after adding the fuel stabilizer. This will ensure that the stabilizer enters the entire fuel system. We also recommend topping out your tank to prevent any extra condensation that could occur while in storage.
The STA-BIL 22207 is an excellent fuel stabilizer for any gasoline engine that you’d like to put into storage for up to two years. It will keep the fuel fresh and lengthen the lifespan of your engine.
Best Overall: STA-BIL 22275 Ethanol Treatment
STA-BIL Ethanol Treatment is a good all-round fuel stabilizer that can be used for in-season performance and well as storage.
The STA-BIL Ethanol treatment will remove water and condensation from your ethanol fuels and keep your marine engine safe. We recommend using it in season to keep your fuel fresh and preserve your engine.
This fuel stabilizer also boasts ‘vapor technology’, which rises to the top of your fuel, keeping it condensation free while storing you boat. This will prevent corrosion, keep your fuel fresh, and add to the longevity of your engine.
STA-BIL Ethanol Treatment is not designed for long term storage (a year or two is too long). That said, for anyone who stores a boat 6 months out of every year, this is the best all rounder stabilizer. You can use it for clean fuel during the season and know that it is protecting it off season.
We would recommend STA-BIL Ethanol Treatment for someone who uses their boat 6 months out of the year and stores it for 6 months during the off season. You’ll only have to buy one product for your fuel, saving energy and money. You can also rest easy knowing that your engine is in good hands and will last a long time.
Most Fuel Treatment: PRI Fuel Stabilizer For Gasoline
For a fuel treatment that you can use regularly to keep your marine engine running smoothly and servicing your engine, we recommend the PRI Fuel Stabilizer.
PRI is developed for gasoline fuel for large engines that have a large tank of fuel attached. While you may not use the entire tank of fuel in one or two trips, you don’t want to end up topping up your fuel on top of gasoline fuel that’s degraded.
Gasoline fuel, especially in a marine environment degrades extremely quickly, in many cases within a month or two. Rather than taking the risk, buy a few bottles of PRI Fuel Stabilizer and keep your fuel clean and fresh.
PRI will also prevent degraded fuel from causing misfires and gumming up your engine components. We would recommend that you add some of this every time you fuel up while you are actively using your boat.
PRI is not a storage fuel stabilizer, so we would recommend that once you are looking to store your boat that you rather start with a fresh tank of fuel and a storage stabilizer like STA-BIL.
This fuel stabilizer is perfect for regular use and will not turn into sludge at the bottom of your engine, but will mix smoothly and cleanly for a safe and clean marine experience.
Best Value: Star Tron Enzyme Fuel Treatment
Star Tron Enzyme Fuel Treatment has an ethanol treatment that most regular stabilizers don’t contain: it breaks down water and gunk to keep fuel clean and clear. This results in more complete and uniform combustion, maximum performance, increased fuel efficiency, reduced emissions and reliable operation.
To everyone suffering from using ethanol fuel, this stabilizer is the perfect solution for an in season marine fuel stabilizer. Keep your boat, no matter how old or new running smoothly and happily.
This will also keep your engine rust free, remove any stoppages from your fuel lines, and in general keep your engine in a healthy condition.
While you may be forced to use standard ethanol fuel for your marine tank, you don’t have to worry about how it’s going to degrade, corrode your engine, or simply not combust correctly while you’re using the Star Tron Enzyme Fuel Treatment.
We would recommend a quart of Star Tron, as that is the strongest concentration, but overall this is a strongly concentrated product that will last you a long time.
You can also use Star Tron for storage. It will keep fuel fresh for up to two years while in storage, and remove water and other impurities from your fuel.
This is an excellent fuel stabilizer for both in season treatment and out of season storage that we would highly recommend to marine enthusiasts with small motors.
Most Reliable: LUCAS Fuel Treatment
This marine stabilizer has been formulated specifically for marine use, and for that reason it’s a fantastic product for those of us looking for a stabilizer for our boats.
Ethanol fuels attract water like nobody’s business, but this treatment will keep your fuel water free. If you have a boat that runs ethanol fuels like E10 and E15, we would certainly recommend this treatment for regular use.
We are all familiar with the destructive effects of ethanol fuel. It breaks down rubber and plastic engine parts like fuel lines, gaskets and eventually it will corrode a fuel tank. A treatment like this one is a sure-fire way to prevent all that from happening.
You know you’re getting great value for money with such a large quantity, making this the best budget option for a treatment that you’re using regularly, especially if you’re servicing more than one engine at a time.
Your overall performance should also increase, giving you more mileage from a tank. This is due to the way this treatment rids your fuel of impurities, allowing it to be used more efficiently and run more smoothly.
This will save your boat a lot of gas money, a lot of maintenance money, and give you peace of mind that your engine is being well serviced.
We would recommend this fuel treatment for during your on season, as it does not seem to be optimized for storage.
Buyer's Guide for Fuel Stabilzers
Storage
If you’re looking for a fuel stabilizer to keep your fuel fresh and your engine in pristine condition while you store your boat or other marine equipment, you’ll have different needs than simply for regular use. For a marine fuel stabilizer that created to keep your engine safe while you’re storing your boat, you need to be sure that the product specifies that it is for storage.
Storage treatments will usually include a vapor technology that rises to the top of the fuel in your tank and absorbs moisture, keeping your tank free from rust. Ethanol fuels attract water over time, especially if you’re storing your boat in a boathouse close to the water, this is going to be a key feature of a storage treatment.
We recommend that you store your boat after filling the tank with a fresh tank of fuel on top of a storage treatment. Once you’ve done that, run the engine for a few minutes to allow the treated fuel to cycle through the entire system. This will ensure that nothing gets too gummy while you’re away.
Be sure to check how long a treatment recommends you use it for storage. Some treatments will last for up to 24 months, while others will only last 6 months.
Regular Usage
It’s definitely worth having a treatment that you top your tank up with during the on season. This will prevent misfires, keep your engine healthy, and even add to your gas mileage.
The dangers from water damaging your engine are just as real, or even more so when your engine is in use. If you’re filling up your fuel with E10 and E15 fuel, you’ll want to use a treatment to keep it as clean and clear as possible.
This will add to the general health and longevity of your engine, as well as preventing embarrassing start up and combustion problems that are caused by ethanol fuels that have degraded.
Type of Fuel
You will find stabilizers for ethanol fuels. These are vital, since ethanol fuels will attract water which will damage your entire engine system. Many diesel fuels also contain ethanol, although some marine fuels do not.
For a diesel engine you’ll need different treatments, so be sure to check which fuel you’re using against which fuel treatment you’d like to purchase.
Many diesel fuels run into the problem of growing algae when exposed to marine environments. This is easily preventable with a fuel treatment that addresses the degradation of fuel.
Most fuels that you’ll be using will be ethanol fuels, so although you can be reasonably confident that that’s the case in your situation, be sure before chucking the wrong treatment in the wrong tank.
Efficiency
A simpler reason than keeping your fuel lines serviced with a fuel treatment is engine efficiency. A happy, clean engine that’s combusting fresh fuel will be that much more effective.
Effective fuel burning will give you a noticeable uptick in your fuel mileage, meaning more time out on the water and less time throwing your wallet into your fuel tank.
In the sense that fuel treatments save you money on fuel, save you money on boat maintenance, and save a lot of worry when storing your boat, they’re an overall boost of efficiency that we highly recommend.
