Fuel Facts: The Danger of E85

You might have noticed (!) that the price of gasoline is pretty high. That’s not the topic of this blog. But the high price of gas is a good segue into talking about ethanol in gasoline and how it affects your boat’s performance. 

First, the background. Beginning in 2005, the Environmental Protection Agency (EPA) began requiring gasoline refiners to add ethyl alcohol (ethanol) to their gasoline products.  Ethyl alcohol is not a fossil fuel–it’s made from distilled alcohol derived from cellulose-rich stocks such as corn, sugar cane and wheat. These days, it is also made with corn stalks, grain straw, paper, pulp, wood chips, municipal waste, switchgrass and other sources.

Today, three kinds of gasoline are sold in the United States: E10, E15 and E85. The most common – and the one you probably pump into both your automobile – is E10, which is a blend of 10 percent ethanol and 90 percent gasoline. Environmentalists are pushing for gasoline refiners to increase the formulas to produce more E15 gas (15 percent ethanol and 85 percent gas).  The E85 gas is mostly reserved for special Flex-Fuel vehicles, not for everyday autos.

E10 gasoline generally works like it should in internal combustion engines to power the vehicle in question.  But there is a side effect to using ethanol in boat engines and motors. Ethanol tends to absorb water molecules. Under certain conditions (like sitting in a fuel tank over the winter) the E10 gas can go through what is called phase separation. That means that the ethanol portion of your gas absorbs enough water molecules and separates from the gasoline and sinks to the bottom of your fuel tank.

Worse, if you run that watery gas though your engines, it can result in performance issues: misfiring, bad starting, poor compression and overall sub-optimal performance.

Even worse than that: in certain conditions (like being left alone over time), the watery ethanol gas can eat away at plastic fuel lines, rubber gaskets and even some kinds of fiberglass, like that used in fuel tanks. Any of those conditions are obviously sub-optimal for boaters.

Now, having scared the heck out of you, we want you to know that if you use ethanol-free gas (like the kind that we sell at our marinas and you can find at select gas stations) you can avoid all of these headaches. Yes, it costs more. But a few bucks spent at the pump will save you from the frustration of a motor that is bogged down by bad fuel. 

You do need to be diligent about changing your fuel filters on a regular basis. And when you winterize your boat, we highly recommend allowing an authorized dealer take care of that for you.

At this time, the boating industry (i.e., the boat builders) do not recommend using E15 fuel in your boat. It may be better for the environment (something we’re all behind) but it is not good for the operation of your boat’s engines. 

The marine industry has all kinds of fuel additives that are claimed to be effective in countering ethanol water-absorption and phase separation problems.  Some work, some don’t. We highly recommend talking to our service department for their advice. Our technicians rely on the best practices of boat manufacturers and the experience of years of dealing with these problems, and they are the experts.