10 Best Boat Fuel Stabilizers (Reviews Updated 2022)

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Fuel stabilizers are an important product to protect and maintain your boat because un-treated fuel can spoil and leave your boat dead in the water.   The risk of spoiled fuel is particularly worrisome when using fuel that has ethanol, which is included in most fuel sold in the United States.  Fuel stabilizers prevent “phase separation” which causes water to form in gasoline.  Our guide reviews different fuel stabilizer products on the market so you can pick the right fuel stabilizer to keep your boat running in top shape.

Best Boat Fuel Stabilizers

Here are our boat fuel stabilizer reviews.

1. Star Tron Enzyme Fuel Treatment Concentrate

Star Tron Enzyme Fuel Treatment Concentrate

The Star Tron Enzyme Fuel Treatment Concentrate is specifically for boats that use ethanol gas that will be kept in storage for an extended time.  The timeframe for using a product like this is typically one year.  If your fuel will sit for one year or more, it is highly recommended to use this product to keep the fuel from separating.  Any gas purchased at a gas station in the United States uses ethanol, only special gas sold at marinas is non-ethanol.  Be mindful that the 1-year guideline seems like a long time to not operate your boat, but even while you are operating the boat during that time, the fuel in your tank can easily be sitting that long.

  • Cures and prevents ethanol fuel problems including phase separation
  • For everyday use and seasonal storage
  • Stabilizes fuel for up to 2 years
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2. STA-BIL 22214 Red Fuel Stabilizer

Sta Bil 22214 Red Fuel Stabilizer (32 Oz.), 32. Fluid Ounces

STA-BIL Red Fuel Stabilizer is another storage product designed to treat ethanol-based gas.  While the typical guideline is to use these products if your fuel will sit for over one year, ethanol gas should also be treated with a product such as STA-BIL if ethanol gas will be mixed with pure gas from a marina.

  • Keeps fuel fresh for up to 24 months during storage
  • Eliminates the need to drain fuel before storage
  • Ensures quick, easy starts after storage
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3. STA-BIL 360 Marine Ethanol Treatment and Fuel Stabilizer

Sta Bil 22239 12pk 8 Oz. (pack Of 12) (22239) 360 Marine Ethanol Treatment And Fuel Stabilizer

STA-BIL 360 Marine Ethanol Treatment and Fuel Stabilizer is specifically designed for boats and can be used any time you use ethanol gas, even if the boat will not be in storage.  This fuel treatment prevents water from collecting in fuel, which ethanol gas is particularly prone to because when ethanol separates over time it attracts water from humidity in the air.  When water collects in fuel the water sinks to the bottom of the fuel tank.  Unfortunately, water in the bottom of a fuel tank is the first substance to be ingested by the fuel lines and it is the most difficult to drain from a boat because there is no way to drain from the bottom of most boat fuel tanks.

  • America’s #1 Ethanol Treatment
  • Advanced formula for engines used in water environments, to better remove moisture
  • Helps prevent corrosion damage by removing water
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4. Yamaha Fuel Stabilizer and Conditioner

Yamaha Acc Fstab Pl 32 Fuel Stabilizer & Conditioner

The Yamaha Fuel Stabilizer and Conditioner is the OEM (Original Equipment Manufacturer) fuel conditioner for Yamaha engines.  If you own a Yamaha engine and you follow manufacturer maintenance guidelines this is the product you should use.

  • Manufacturer recommended product for Yamaha engines
  • Provides corrosion protection for metal fuel system components
  • The alcohol-free formula that prevents fuel oxidation, phase separation, gum, and varnish build-up
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5. Mercury Quickare Fuel Treatment Additive

Mercury Quickare Fuel Treatment Additive

Mercury’s Quicksilver Quickare Fuel Treatment Additive is the manufacturer recommended additive for Mercury engines.  Use one ounce of this product for every 10 gallons of gas with every fill-up to maintain manufacturer-recommended protection for your engine from ethanol gas.

  • Great for cleaning existing deposits in untreated fuel lines
  • Keeps fuel fresh for up to three months
  • Can be used in all 2 and 4 cycle carbureted and fuel-injected gasoline engines
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6. STA-BIL 360 Protection Ethanol Treatment and Fuel Stabilizer

Sta Bil 32 Ounces (22275) 360 Protection Ethanol Treatment And Fuel Stabilizer

STA-BIL 360 is formulated to protect engines from the harm caused by ethanol gas.  This formula is designed for use in boats as well as small engines such as lawnmowers.

  • Helps prevent ethanol fuel related damage in vehicles and small engines
  • Increases engine power and efficiency
  • Keeps fuel fresh for up to 12 months
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7. Fuel Ox Marine Complete Fuel Treatment and Combustion Catalyst

Fuel Ox Marine Complete Fuel Treatment And Combustion Catalyst

Fuel Ox Marine is not just a fuel stabilizer, it also includes a patented combustion catalyst.  This combustion catalyst increases power and fuel economy, while also protecting your fuel from the harmful effects of ethanol.

  • Patented combustion catalyst increases fuel economy
  • Protects against corrosion caused by ethanol gasoline
  • Highly concentrated formula treats both gas or diesel
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8. STP 17438 Ethanol Fuel System Treatment

Stp 17438 Ethanol Fuel System Treatment 12 Fl. Oz

STP Ethanol Fuel System Treatment is designed to protect your engine from the harmful effects of ethanol.  You may choose to use this product if your boat motor shows signs of being particularly susceptible to ethanol gas, such as backfiring, idling rough, or running excessively hot.

  • Inhibits corrosion and stabilizes fuel
  • Prevents ethanol deposits
  • Works with 2 and 4 stroke engines
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9. Sta-Bil Diesel Formula Fuel Stabilizer and Performance Improver

Sta Bil 22254 Diesel Formula Fuel Stabilizer And Performance Improver

If your boat has a diesel engine, you will not have to worry about ethanol.  However, diesel engines are prone to sludge and carbon deposits.  This Sta-Bil diesel formula protects your engine by treating your diesel fuel to reduce these deposits.

  • Prevent sludge and sediment formation
  • Clean and lubricate the entire fuel system
  • Helps remove water that bacteria, fungus, and algae require to grow
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10. Sea Foam

Sea Foam 1 Pack (16 Ounce) Extreme Marine & Rv Sf 16 Seafoam Liquid

Sea Foam has a legendary reputation among boat owners.  Not only does Sea Foam stabilize your fuel, but it is also known as a “mechanic in a bottle” for its ability to restore carburetors, fuel injectors, and pistons by cleaning your engine while the engine is running.  Sea Foam is a great choice not only for stabilizing fuel but for cleaning and healing an engine that shows signs of difficulty.

  • Cleans injectors, carb jets, and passageways
  • Cleans and lubricates intake valves, pistons, and cylinders
  • 100 percent pure petroleum
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Boat Fuel Stabilizers Buyer’s Guide

Best Boat Fuel Stabilizers ReviewWhen choosing a fuel stabilizer it is most important that you understand your boat’s fuel and engine so that you can choose the right stabilizer based on your needs.  For gas engines, there are two types of fuel; ethanol and non-ethanol.  Ethanol gas is found at any gas station in the United States.  If you fill our boat’s gas tank at a gas station you are using ethanol gas.   Ethanol is harmful to boat engines because ethanol attracts water and because ethanol separates from gasoline over time.  The accumulation of water causes corrosion on your boat’s fuel system components.

Ethanol gas does not necessarily require treatment from a fuel stabilizer if the gas is used quickly, if your boat’s engine does not suffer while burning ethanol gas, and if you do not plan to mix ethanol gas with pure gasoline.  However, for most boat owners one or more of these conditions will usually apply.  Boat owners often fill their tank but may not use an entire tank of gas in a year, leaving plenty of time for the fuel to separate and damage to occur.  If boat owners happen to top-off the tank at a marina then they will be mixing ethanol and non-ethanol gas.  This mixture can cause a sludge to form that quickly kills the engine.  This will require changing the fuel filter and partially raining the fuel system to fix.

If your boat has a diesel engine, then your fuel should be treated with an entirely different type of fuel stabilizer.  Diesel fuel for diesel engines is not made with ethanol and is much less prone to water accumulation.  To protect your engine with clean running diesel, you may consider a product such as Sta-Bil Diesel Formula.