Ahh…. The great debate.  Is E10/Ethanol Fuel ok to run in your boat?  Or should you stick with Ethanol-Free Fuel?

First off—we here at Smart Ass Products don’t really have a dog in this fight.  The Smart Ass Fuel Mule Fuel Caddy doesn’t care what fuel you use.  Whether you save $2/gallon compared to marina prices buying non-ethanol fuel at a local gas station, or whether you save $2.50/gal by buying ethanol blend/E10 fuel, we don’t care. We're here for you.  

In case you haven't seen a Smart Ass Fuel Mule Fuel Caddy in action before in it's native environment, here's your chance!

Bottom Line - Be a Smart Ass:  Go forth and save ye time and money!!!  We’ll help you do that either way!   (And this 50 gallon Gas Caddy is so easy to use!)

 

So back to the great debate….  To consume Ethanol or not to consume Ethanol, that is the question.

People get straight up ornery about this sometimes.  Declaring from the rooftops that anyone that thinks differently than they do is just dead wrong and deserving of the greatest form of social media comment section ridicule and shame. 

At great risk, ok, guarantee, of bringing about some of that comment section commotion upon ourselves - we’ll chum the water a little bit here.  I’m Jerry Hoffmann, the creator of the Smart Ass Fuel Mule, and the founder of Smart Ass Products.  In my past life, I founded and operated a business for 19 years (DIYAutoTune.com) that manufactures race car Engine Management Systems that control the fuel injection, ignition, nitrous, turbocharger boost levels, and all kinds of other whiz-bang race car features, and that ultimately lets you tune your engine to perfection from a laptop computer.  Basically-- I designed and manufactured computers that control the engines in race cars.  With a thousand different settings that control literally every aspect of how an engine operates and gives the user the control needed to make in some cases thousands of horsepower from a single engine.  This is me doing a little land speed racing a few years ago….  This particular car makes about 1000whp from an engine that from the factory made about 1/3 of that.  (yes I still have the car)

 

 

In the process of running that company, I also co-wrote a book on Performance Electronic Fuel Injection Systems.  So while I won’t claim to know everything about everything or anything close to that.  It is rumored I may at least know a little bit about Fuel Injection Systems and different types of fuel running through them.  That knowledge and $8 gets me a cup of coffee at most overpriced coffee shops.

So what do I think?  Here goes….  

It depends. 

Commonly, you’ll hear that using ethanol-free fuel in a boat is generally recommended.  Bottom line, it’s never a bad thing.  It is the most risk adverse choice and as such, does avoid the potential risk of some issues.  But that said, it’s not always of any real benefit at all.  It can be a wasted hassle and expense in many cases.  So it helps to understand where the line is.  Ultimately, whether ethanol-free fuel is necessary for your boat or not depends on your boat's engine, your usage habits, and your storage habits.

 

Here’s a breakdown of the pros and cons of using ethanol-free fuel versus ethanol-blended fuel:

Potential Benefits of Ethanol-Free Fuel In Boats:

1. Reduces Chance of  Water Contamination:
• Ethanol is hygroscopic, meaning it absorbs moisture from the air. In a marine environment, where humidity is high, this can lead to phase separation (a layer of water forming in the fuel tank), which you obviously don’t want.
2. Reduces Chance of Corrosion:
• Ethanol can cause corrosion in fuel system components, particularly in older engines not designed to handle ethanol blends. This is especially true for carburetors, fuel lines, and fuel tanks on older vessels.
3. Long-Term Storage Considerations:
• Boats are often stored for months at a time. Ethanol-free fuel is more stable over time and less likely to degrade, making it ideal for extended periods of inactivity.  First off, use your boat more!!!   But if you don’t, then there is some value in non-ethanol fuels.  Or you can do what I sometimes do—use E10 all season, and run a tank of non-ethanol fuel through it prior to winterizing, and leave a full tank of non-ethanol fuel in it over the off season.
4. Better Compatibility with Older Engines:
• Many older boat engines were designed before ethanol-blended fuels became common. Using ethanol can degrade seals, gaskets, and other components in these engines.

 

Noticing a trend?

If you’re paying attention you probably are, a trend that makes the main determination in whether or not running ethanol blended fuel is acceptable for you and your boat.  It’s actually a pretty simple line that make that determination primarily, and a secondary consideration that will impact some.  We’ll get to that simple conclusion in just a moment. 

Let’s look at what commonly makes ethanol fuels an excellent choice for some boaters next….. 

 

When Ethanol-Blended Fuels May Be a Good Idea:

1. Modern Engines:
• Many newer marine engines (built after the mid-2000s) are designed to run on ethanol-blended fuels (up to 10% ethanol, E10). They we designed specifically to use this fuel, and use materials and components that resist ethanol-related damage.
• Furthermore, the emissions systems on modern boat engines implement EVAP (evaporative emissions) systems that reduce the permeability of the fuel lines, fuel tank, and other fuel system components as well as control the venting of the fuel system to atmospheric air.  This reduces and otherwise controls/prevents the exchange of outside air and the air inside your fuel tank and fuel system components.  Without air exchange, water can’t get in as it does with unsealed, older, fuel systems that allow more free air exchange allowing the outside air to carry humidity into the fuel system where it can condense into the fuel, and particularly into fuel with ethanol due to it’s hygroscopic properties. 
• You can use your Smart Ass Fuel Mule motorized gas caddy to buy E10 at your local street gas station and save a TON of money compared to buying marina fuel.   (But what you’re really going to love is the time you save doing it this way!)
2. Regular Usage:
• If you use your boat frequently and refill the tank often, there’s less time for ethanol to absorb moisture or cause phase separation (a layer of water in your fuel tank).  Bottom line—USE YOUR BOAT!!   You needed another excuse to do that didn’t you?  You’re welcome!  😉
3. Proper Storage Practices:
• If you do store your boat for long periods, and you’re running ethanol blend fuel, using stabilizers specifically designed for ethanol-blended fuels can reduce the risks associated with ethanol, such as phase separation and varnish buildup.  That said, you can easily run ethanol fuel all season and just run a tank of non-ethanol fuel through the boat before storage and store it with a full tank, and I think you’ll find that does the trick just fine. 

 

 

What does your boat/engine manufacturer have to say about the topic?

You’re a Smart Ass.  I’m sure you are noticing the key elements that really make the difference here.  Older boats with older engines were not designed for ethanol fuels.  The materials that the tanks, lines, and other components were made out of were not designed to deal with the challenges that ethanol presents to them.

On the flipside—your modern boat, with modern engine that WAS designed for ethanol fuels, and whose owners manual from the manufacturer DOES recommend ethanol fuels, is going to be just fine. 

The above is from my 2021 Supra SA400's Engine Owner's Manual for the Raptor 6.2.  Mid-grade (89 octane) E10 fuel is an approved fuel.  

This chart is from a modern Centurion Boat Owner's Manual.  Again showing that that E10 is approved and warranted by the manufacturer.

With a Modern Boat/Modern Engine (beginning in the early 2000’s and very common in 2010 and newer) from a Manufacturer that recommends E10 Fuel---   You should be able to run E10 fuel with no concern, with just a few best practices to consider…

 

Best Practices for Fueling your Boat:

1. Always always always, use your Smart Ass Fuel Mule Gas Caddy to make your life easier:  Saving yourself time and money fueling your boat while saving your back and eliminating wasteful and environment damaging spills from leaky fuel jugs.  Repeat after me:  “NO MORE LUGGING JUGS AND NO MORE RIDICULOUS MARINA UPCHARGE!!”   [/end shameless plug]
2. Use Ethanol-Free Fuel on Older Engines that don’t specifically recommend E10 fuel:
• Just do it.  Or buy a newer boat/engine.    
3. If Using Ethanol-Blended Fuel on Modern Boat Engines that recommend it:
• Ensure your fuel contains no more than 10% ethanol (E10).
• Consider adding a marine fuel stabilizer to reduce moisture absorption and protect against phase separation if you’re storing your boat for longer periods.
4. During Storage:
• This is where, even if your boat manufacturer recommends E10 fuel as acceptable for your engine, it’s not a bad idea to store your boat with non-ethanol fuel in it.  You can save money all season running E10, then just put non-E in the boat for storage at the end of the season.  Run it for a few minutes to burn all the E10 fuel out of the fuel system, and put ‘er up with a full tank.
• In all cases-- A full tank minimizes airspace and reduces the chances of moisture collecting in your fuel.  Less room for air in the tank is less room for air to be exchanged with outside air, reducing the ability of that air to bring in humidity that can condense in your tank. 
• I keep saying I’m gonna do this myself…. And then I usually don’t.  That said, I never let my boat sit too long before I find a nice warm day to get it back out.  Here in Georgia we’ve been known to have the occasional mid-70’s day even in late December and early January and get out for a quick surf set!  
5. Follow Manufacturer Recommendations:
• Always check your engine’s manual for fuel specifications and follow the manufacturer’s guidelines.  If they say it’s OK to use E10, it’s OK to use E10.  

 

Go forth, be a Smart Ass, and enjoy the water!!!