top of page

A Common Mistake

This is a hot button topic so don't get too worked up over it!

Gas prices continue to rise in this world. We're all looking to save a few bucks as well. You've probably considered, a time or two, just grabbing the ole jerry cans from the shed and topping off the boat with the same trusty 87 octane fuel that your car gets. You're thinking, "why not?" You might save yourself a couple bucks on the gallon right now. Every little bit helps, right? WRONG!

We're going to give you some stories and advice as a marina that is no longer in the business of selling gas. So do not think we are just here to push a more expensive fuel to make money. Mind you, we never made money on our gas sales anyway.

I'm going to start by going through the adverse effects of using ethanol-based fuels in your marine engine.

1) Ethanol fuel has a shelf-life of approximately 90 days. Engines are getting more and more fuel efficient, and boats are getting larger fuel tanks than ever before. We have many customers who only use one tank every season. Obviously, this poses a problem right away. As soon as that gas goes bad, the hygroscopic effects of ethanol kick in...which brings me to my next point.

2) Ethanol is hygroscopic. For those who don't know what that means, it's the opposite of hydrophobic. Ethanol attracts water. It's common practice for condensation to occur in your fuel tank, especially in the spring and fall seasons. Ethanol will absorb that water. As much as we'd love an engine that runs on water, we're not quite there yet. Therefore, WATER IN GAS IS BAD!

3) Ethanol can cause fuel lines, fuel filters, and fuel injection/carburetion components to break down at a faster rate. Don't believe it? Spray ether on a piece of plastic or rubber. Ether and ethanol are extremely similar in structure. They will cause plastic and rubber to deteriorate. I promise you, a lot of your marine engine's fuel system is plastic and rubber.

"But TJ my owner's manual says I can use up to 10% ethanol fuel in my boat!" Ok. You got me. Yes, that might be true. However, when you go to the gas pumps do you test the fuel for ethanol content before you fill your boat up with it? Of course not. That's too much work. Are you going to just trust that sticker on the pump? Even if it is only 10% ethanol, let's refer back to the shelf-life of ethanol fuel.

"But TJ I use ethanol fuel in my car and truck." Boy, you guys have a lot of comebacks today. Anyway, yes you use ethanol fuel in your vehicle without any issues. First, if your car is newer than a 2012, it's specifically designed to run ethanol-based fuels per government regulations. If you're still driving around in a classic car, do yourself a favor and use non-ethanol fuel for the same reasons I've been talking about. Another reason you're not running into problems in your car is back to the shelf-life. Not often do you have gas older than 3 months in your gas tank. You're more likely to combat the hygroscopic effects of ethanol by burning through the fuel more often.

Let's go over the advantages of using non-ethanol fuel.

1) Non-ethanol fuel is more efficient than its ethanol-based counterpart. Pure gasoline has a higher energy content, therefore it takes less of it to deliver the power you expect from your boat engine.

2) Non-ethanol fuel prolongs the life of your fuel system. Less time in the shop, and more time on the water. That's the dream! We all love being on our boats and nothing ruins the summer more than chasing down fuel system problems.

3) Non-ethanol fuel has a much longer shelf-life. Let's say you're the proud owner of a Manitou V-Toon. That means you have 44 gallons of gas in that bad boy when it's full! Basic non-ethanol fuel has over double the shelf-life of its ethanol-based counterpart, and if you're using ValvTect treated marine fuel, it's even longer than that!

Alright, this is the last part. I promise. Let's go over the main reason why anyone would want to use ethanol fuel instead of non-ethanol fuel. CHEAPER. But, is it?

Let's do some quick math. On average, our customers use less than 50 gallons of fuel per season. Many people use even less than that. However, for this example, we're going to use current fuel prices and 50 gallons. Our current fuel price is $4.899 for our 90 octane non-ethanol ValvTect marine fuel. The current regional average price for 87 octane E10 fuel is $3.329. For those of you without a calculator handy, that's a $1.57 difference per gallon. Therefore, if you use 50 gallons per season, you're going to save $78.50 by using that ethanol fuel on the street. You'll be able to afford to take your family of four out to dinner with that....maybe. But what you're not considering is the additional service work that's inevitable when running that gas in your boat.

Let's say that beautiful Manitou V-Toon came equipped with a Yamaha VF150 V-Max SHO. Great motor and I'm really proud of you for choosing it (although we all know you wanted to go bigger). You're using ethanol-based fuel in that boat and, OH NO, your fuel line started leaking from the ethanol eating away the interior liner. No worries, you're going to call Casey's Cove Marina and have their expert team fix it for you! Smart move. $110 in labor and $100 in parts later, you're back on the water (plus transportation fees). That's just a simple one. Let's look at another.

That same more starts running really rough and the 4th of July is staring you in the face. You can't keep that motor running right now and every marina within an hour drive is backed up 3 weeks on their turnaround time. So now you're stuck with a floating barge that won't run. For arguments sake, let's say we get it in the shop before then. We find water in your fuel tank, fuel filter is junk, and 2 injectors are shot (it's common practice with ethanol fuel). So $440 in labor, $300 in parts, plus fuel disposal fees (and probably transportation). Let's call it $800. Glad you saved $80 on your gas budget now?

I digress. This blog was a lot of fun. And for those of you reading it, I'm glad you stuck it out to the end. I hope you learned something today. Saving a few bucks here and there on gas is a great idea in the short-term. However, I promise you, it'll cost you one way or another.

128 views0 comments

Recent Posts

See All


bottom of page