The Best Ethanol Fuel Treatments for Boat Engines

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If you’re a boat own­er, you’re no stranger to the con­tro­ver­sial rela­tion­ship between boats and ethanol-blend­ed fuels. 

Our pick

Our Score:


  • Pre­vents fuel cor­ro­sion
  • Works best on small motors
  • Excel­lent fuel-keep­ing abil­i­ty

Also good

Our Score:


  • Easy-to-use
  • Keeps fuel fresh for a long time
  • Makes engines start eas­i­ly and run smooth­ly

Most reviewed

Our Score:


  • Pro­vides active pro­tec­tion
  • Helps engines start smoother
  • Great val­ue for low price

It’s like the plot of a day­time soap opera — some­times it works out, but often it’s a dra­ma-filled deba­cle. And that’s where ethanol fuel treat­ments stride onto the scene. They’re the heroes, sav­ing your boat engine from the poten­tial­ly dam­ag­ing effects of ethanol. But like any good cast, not all heroes are cre­at­ed equal. Some shine brighter than oth­ers.

The Best Ethanol Fuel Treatments for Boat Engines

The best ethanol fuel treat­ments for boat engines depend on the type of engine and fuel sys­tem, as well as the fuel used. Fuel sta­bi­liz­ers are rec­om­mend­ed, as ethanol has a ten­den­cy to break down more quick­ly than oth­er fuel sources. Marine-spe­cif­ic fuel addi­tives may improve per­for­mance and reduce the effects of ethanol on the engine.

1. STA-BIL 360 Marine Ethanol Treatment & Fuel Stabilizer 

  • Com­plete­ly cleans the entire fuel sys­tem
  • Pre­vents fuel cor­ro­sion
  • Works best on small motors
  • Excel­lent fuel-keep­ing abil­i­ty

This is the real deal! It vapor­izes to pro­tect above the fuel line where untreat­ed addi­tives can’t reach. This means it pro­vides a more com­pre­hen­sive form of pro­tec­tion, safe­guard­ing your entire fuel sys­tem from the harm­ful effects of ethanol-blend­ed fuel. Plus, STA-BIL has been in the game for over 60 years, which is like for­ev­er in the world of fuel addi­tives.

2. STAR BRITE Star Tron Enzyme Fuel Treatment

  • Easy-to-use
  • Keeps fuel fresh for a long time
  • Makes engines start eas­i­ly and run smooth­ly
  • Helps pre­vent phase sep­a­ra­tion

This one is a star, and not just because it’s in the name. The unique enzyme tech­nol­o­gy helps to break down debris and water in the fuel, which can cause phase sep­a­ra­tion in ethanol-blend­ed fuels. Phase sep­a­ra­tion can be dis­as­trous for your engine, so this is a big­gie. Plus, users rave about how it improves their boat’s per­for­mance and fuel effi­cien­cy.

3. Lucas Oil Safeguard Ethanol Fuel Conditioner with Stabilizers

  • Pro­vides active pro­tec­tion
  • Helps engines start smoother
  • Great val­ue for low price

I like to think of this one as the pro­tec­tive big broth­er of your fuel sys­tem. It con­tains pow­er­ful deter­gents and cor­ro­sion inhibitors that pre­vent the nasty side effects of ethanol, keep­ing your engine clean and hap­py. It’s also super con­cen­trat­ed, so a lit­tle goes a long way.

4. STA-BIL 360 Protection Ethanol Treatment & Fuel Stabilizer

  • Excel­lent fuel clean­er
  • Pro­tects to pre­vent fuel cor­ro­sion
  • Improves engine per­for­mance

This one is a bit of a mav­er­ick. It com­plete­ly cleans the entire fuel sys­tem from fuel injec­tors to fuel pumps, and removes water, gum, and var­nish to keep your fuel sys­tem free of cor­ro­sion.

NOTE: Remem­ber, even with these pow­er­ful side­kicks on board, it’s still a good idea to fill up with non-ethanol fuel when­ev­er pos­si­ble.

  • When select­ing the best ethanol fuel treat­ment for a boat engine, it is impor­tant to ensure that the prod­uct is com­pat­i­ble with the type of fuel used and the engine mod­el. Dif­fer­ent fuel treat­ments have dif­fer­ent com­po­nents, such as deter­gents, cor­ro­sion inhibitors, and lubri­cants. These com­po­nents can help to reduce the risk of clogged fuel lines and fuel injec­tors, as well as improve engine per­for­mance. Check our arti­cle: how to clean out a boat gas tank
  • It is also impor­tant to use the cor­rect amount of fuel treat­ment for the size of the engine, as too much or too lit­tle can cause engine dam­age. It is best to use the fuel treat­ment at least once a sea­son to ensure that the engine is run­ning opti­mal­ly.

Ethanol fuel is a type of fuel that is derived from renew­able sources, such as corn, sug­ar­cane, and oth­er plant-based mate­ri­als. It is a pop­u­lar choice for boat own­ers because it is more afford­able than tra­di­tion­al gaso­line and cre­ates few­er emis­sions. Ethanol fuel is also less volatile than gaso­line, mean­ing that it is less like­ly to evap­o­rate or ignite in high tem­per­a­tures.

What are the Benefits of Ethanol Fuel for Boats?

The main ben­e­fit of using ethanol fuel is that it is more afford­able than tra­di­tion­al gaso­line. It also pro­duces few­er emis­sions, mak­ing it a more envi­ron­men­tal­ly-friend­ly option. Ethanol fuel has a high­er octane rat­ing than tra­di­tion­al gaso­line, which can improve engine per­for­mance and fuel effi­cien­cy.

Yes, ethanol gets a bad rap, espe­cial­ly when we’re talk­ing boats. But it’s not all doom and gloom. There are actu­al­ly a few ben­e­fits to ethanol fuel for boats. So let’s have a look, shall we?

  • Renew­able and Envi­ron­men­tal­ly Friend­ly: Ethanol is made from renew­able resources like corn and sug­ar­cane. This makes it a more sus­tain­able fuel choice com­pared to petro­le­um-based gaso­line. Plus, when burned, ethanol pro­duces less car­bon diox­ide, a green­house gas con­tribut­ing to cli­mate change. So, if you’re an eco-con­scious boater, ethanol could be a good option.
  • Boosts Octane Lev­el: This is where things get a lit­tle geeky (in a good way, I promise!). Ethanol has a high octane rat­ing. Why should you care? Because high octane fuels can help pre­vent engine knock­ing, improv­ing your boat’s per­for­mance.
  • Wide­ly Avail­able: It’s pret­ty easy to find ethanol-blend­ed fuels at mari­nas and gas sta­tions. Plus, in some coun­tries (like the USA), ethanol-blend­ed fuels can be less expen­sive than pure gaso­line.
  • Sup­ports Local Econ­o­my: Since ethanol is often pro­duced from crops like corn and sug­ar­cane, buy­ing ethanol-blend­ed fuels can sup­port local farm­ers and the agri­cul­tur­al indus­try.

Ethanol fuel offers sev­er­al ben­e­fits for boat own­ers. It is a renew­able fuel source that is less harm­ful to the envi­ron­ment than tra­di­tion­al petro­le­um-based fuels. It is also less expen­sive than gaso­line. It is eas­i­er to trans­port and store than gaso­line, as it has a low­er vapor pres­sure, which reduces the risk of explo­sions. It can also improve engine per­for­mance, as it can help reduce emis­sions, improve fuel econ­o­my, and reduce engine wear.

It is also designed to be com­pat­i­ble with exist­ing boat engines and com­po­nents, reduc­ing the need for cost­ly mod­i­fi­ca­tions or replace­ments. It is also less like­ly to cor­rode met­al com­po­nents, mak­ing it a bet­ter choice for boats that must be exposed to harsh con­di­tions. It helps reduce engine noise, mak­ing it an ide­al choice for those who want qui­eter boat­ing expe­ri­ences. Ethanol fuel can also help reduce the amount of main­te­nance need­ed for boat engines, as it is less like­ly to form deposits on engine com­po­nents.

What are the Drawbacks of Ethanol Fuel?

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While ethanol fuel has many ben­e­fits, it also has some draw­backs. One of the most sig­nif­i­cant issues with ethanol fuel is that it is more prone to evap­o­ra­tion and sep­a­ra­tion. This means that it can cause fuel lines and fil­ters to become clogged, lead­ing to reduced engine per­for­mance. It can cause cor­ro­sion in some boat engines, lead­ing to fur­ther issues.

  • Cor­ro­sion and Dam­age: Ethanol is a sol­vent and can be cor­ro­sive. This can cause dam­age to rub­ber and plas­tic parts of the fuel sys­tem, which is bad news for old­er boats that weren’t built with ethanol-resis­tant mate­ri­als.
  • Water Absorp­tion: Ethanol loves water. It absorbs it right out of the atmos­phere. Too much water in your fuel can lead to phase sep­a­ra­tion, where the water-ethanol mix sep­a­rates from the gaso­line and sinks to the bot­tom of the tank. This can cause some major headaches, includ­ing engine dam­age and fuel sys­tem clogs.
  • Decreased Fuel Effi­cien­cy: Ethanol has a low­er ener­gy den­si­ty than gaso­line, which means you’ll burn more fuel and have to fill up more often. And more trips to the pump means less time out on the water, which is a real bum­mer.
  • Short Shelf Life: Ethanol-blend­ed fuels have a short­er shelf life than pure gaso­line. If the fuel sits in your tank for too long (like dur­ing off-sea­son stor­age), it can break down and cause a whole slew of prob­lems, includ­ing gummed-up fuel lines and poor engine per­for­mance.

A fuel treat­ment is a prod­uct that is added to the fuel to help pro­tect and enhance the per­for­mance of an engine. Fuel treat­ments are designed to help reduce evap­o­ra­tion and sep­a­ra­tion, and pre­vent the buildup of deposits in the fuel sys­tem. Fuel treat­ments can help reduce cor­ro­sion and main­tain the fuel system’s over­all health.

What are the Different Types of Fuel Treatments?

There are sev­er­al dif­fer­ent types of fuel treat­ments avail­able on the mar­ket. The most pop­u­lar types of fuel treat­ments for ethanol fuel include sta­bi­liz­ers, anti-cor­ro­sion addi­tives, and deter­gents.


Sta­bi­liz­ers are designed to help reduce the evap­o­ra­tion and sep­a­ra­tion of ethanol fuel, allow­ing it to main­tain its con­sis­ten­cy over time. Sta­bi­liz­ers also help to pre­vent the buildup of deposits in the fuel sys­tem, keep­ing it clean and effi­cient.

Anti-Corrosion Additives

Anti-cor­ro­sion addi­tives are designed to help pre­vent cor­ro­sion in the fuel sys­tem. These addi­tives help to pro­tect the fuel lines, fil­ters, and oth­er com­po­nents from dam­age caused by ethanol fuel.


Deter­gents are designed to help keep the fuel sys­tem clean and free of deposits. They help to break down and remove any exist­ing deposits, allow­ing the fuel sys­tem to run more effi­cient­ly.

Which Fuel Treatment is Best for Boat Engines

Noise and Vibration Reduction

The best fuel treat­ment for boat engines depends on the type of fuel being used and the con­di­tion of the engine. In gen­er­al, sta­bi­liz­ers and anti-cor­ro­sion addi­tives are the best options for ethanol fuel, as they help to pre­vent evap­o­ra­tion and sep­a­ra­tion, as well as cor­ro­sion. Deter­gents can also be ben­e­fi­cial, as they help to keep the fuel sys­tem clean and effi­cient.

Why are Fuel Treatments Necessary

Using fuel treat­ments is essen­tial for ensur­ing the longevi­ty and per­for­mance of your boat engine. Fuel treat­ments help to reduce evap­o­ra­tion and sep­a­ra­tion, pre­vent cor­ro­sion, and keep the fuel sys­tem clean and effi­cient. Addi­tion­al­ly, fuel treat­ments can help to improve fuel effi­cien­cy and reduce emis­sions. All of these ben­e­fits add up to a boat engine that will run smoother, last longer, and be more reli­able.

How to Choose a Fuel Treatment

You’ve got to under­stand what you’re deal­ing with. If your boat’s engine is run­ning on ethanol-blend­ed fuel, you’ll want a treat­ment that helps to coun­ter­act the poten­tial neg­a­tive effects of ethanol, like cor­ro­sion, water absorp­tion, and phase sep­a­ra­tion. Some treat­ments even help to sta­bi­lize the fuel, which can extend its shelf life (a real plus if you’re stor­ing your boat over the win­ter).

Con­sid­er the age and con­di­tion of your boat. If you’re sail­ing around in a vin­tage beau­ty, she might need a bit more care than a new­er mod­el. Look for a fuel treat­ment that includes deter­gents and cor­ro­sion inhibitors to help keep those old­er engine parts in top shape.

Fuel effi­cien­cy is anoth­er fac­tor. Some treat­ments can help improve com­bus­tion, which can give your fuel effi­cien­cy a lit­tle boost. This might not sound like a big deal, but trust me, every bit helps, espe­cial­ly when you’re out on the water for an extend­ed fish­ing trip or cruis­ing around with friends.

TIP: Don’t for­get to read the reviews. We’re all part of the boat­ing com­mu­ni­ty, and we look out for each oth­er. If a prod­uct has rave reviews and tons of hap­py cus­tomers, chances are it’s doing some­thing right.

Where to Find Fuel Treatments For Boats

Brick-and-mor­tar stores are still in busi­ness. You can vis­it local marine sup­ply stores, big box stores like Wal­mart or Lowe’s, or even auto­mo­tive parts stores. They usu­al­ly have an aisle ded­i­cat­ed to fuel treat­ments and addi­tives.

Before you hit the ‘buy now’ but­ton or head to the check­out, make sure the prod­uct you choose aligns with your boat’s needs, the fuel type you’re using, and the advice we’ve chat­ted about ear­li­er.

TIP: If you’re a first-timer, it’s a good idea to chat with a pro­fes­sion­al or expe­ri­enced boater. It could be a chat with the store atten­dant, your boat mechan­ic, or your boat-obsessed neigh­bor, Gary. They can share their wis­dom, help­ing you make a more informed deci­sion.

How to Use Fuel Treatments for Boats

Using fuel treat­ments is rel­a­tive­ly sim­ple. Most treat­ments require you to add the prod­uct to your fuel tank before fill­ing it up. Some treat­ments require you to add the prod­uct direct­ly to the fuel fil­ter or fuel line. It is impor­tant to read the instruc­tions on the prod­uct label to ensure that you are using the prod­uct cor­rect­ly.

In order to use fuel treat­ments for boats, the first step is to deter­mine what type of fuel treat­ment is need­ed. Depend­ing on the fuel type and engine con­fig­u­ra­tion, dif­fer­ent treat­ments may be nec­es­sary. Once the fuel treat­ment type is deter­mined, it should be added to the fuel tank before fill­ing up with fuel at the mari­na. It should be used at a ratio of 1 oz per 10 gal­lons of fuel. Fuel tank should be filled up with the rec­om­mend­ed grade of fuel. The fuel sys­tem should be checked to ensure that the fuel treat­ment has been prop­er­ly dis­persed and that the engine is run­ning cor­rect­ly.

It is also impor­tant to mon­i­tor the fuel sys­tem after using fuel treat­ments. If any issues arise, the fuel sys­tem should be checked for clogs or oth­er prob­lems. It should be reg­u­lar­ly inspect­ed to ensure that they are in good con­di­tion and not past their expi­ra­tion date. Fuel treat­ments should be used in accor­dance with the manufacturer’s instruc­tions to ensure that they are used prop­er­ly and are effec­tive. Fol­low­ing these guide­lines will help ensure that fuel treat­ments are used safe­ly and effec­tive­ly on boats.

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What does an ethanol fuel treatment do for a boat engine?

An ethanol fuel treat­ment works like a pro­tec­tive shield for your boat engine when you’re using ethanol-blend­ed fuel. It helps pre­vent the cor­ro­sion and dam­age that ethanol can cause to the engine’s com­po­nents. Plus, it helps to pre­vent water absorp­tion (which ethanol is prone to do) and sta­bi­lizes the fuel to extend its shelf life. All this helps your engine run smoother and last longer.

How often should I use an ethanol fuel treatment in my boat?

The fre­quen­cy depends on how often you use your boat and the spe­cif­ic instruc­tions on the treat­ment prod­uct. Gen­er­al rule of thumb is to use it every time you fill up your tank. If your boat is in stor­age or not used fre­quent­ly, it’s a good idea to use a treat­ment before the long sit to help main­tain the fuel qual­i­ty.

Can I use a car fuel treatment for my boat?

While it might be tempt­ing to grab that car fuel treat­ment you have in your garage, it’s bet­ter to use a prod­uct specif­i­cal­ly designed for boats. Boat engines and fuel sys­tems have unique require­ments and are often more sus­cep­ti­ble to dam­age from water and cor­ro­sion, espe­cial­ly when using ethanol-blend­ed fuel.


Ethanol fuel is a pop­u­lar choice for many boat own­ers, as it is more afford­able and cre­ates few­er emis­sions than tra­di­tion­al gaso­line. Using ethanol fuel can also lead to prob­lems with your engine, such as clogged fuel lines and fil­ters, and decreased engine per­for­mance. To com­bat these issues, many boat own­ers are turn­ing to fuel treat­ments to help pro­tect their engines and keep them run­ning smooth­ly. The best fuel treat­ments for boat engines are sta­bi­liz­ers, anti-cor­ro­sion addi­tives, and deter­gents. These treat­ments help to reduce evap­o­ra­tion and sep­a­ra­tion, pre­vent cor­ro­sion, and keep the fuel sys­tem clean and effi­cient.

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