What’s the real story behind E10 fuel and its effects on the boating angler? There is certainly a lot of misinformation out there and there is also a lot of good information. And if you decide that E10 fuel and your boat are not a good fit, how do you find service stations that sell simple unleaded fuel?

Read on and we’ll discuss the pros and cons of E10 fuel, show you how to find service stations that sell unleaded fuel and have a brief discussion on high-octane unleaded fuel and its benefits (or lack thereof) for your boat and motor.

Before we delve into this rich subject, I’d like to acknowledge that this article was the result of the industry helping me out a lot. Every engine manufacturer went above and beyond with their help in regard to research and information provided. Also, Gary Fooks, considered by many as the research expert for outboards in this field, helped enormously. To all, a special thanks.

With that said, let’s get into it.

E10 is a blended ethanol fuel that reduces the amount of petrol in the fuel mix to around 90%. Ethanol is a by-product of broad-acre crop farming (especially sugar cane in Australia) and many years ago the powers that be introduced E10 or similar fuels.

On the surface this sounded fine, especially for the farmers who stood to make extra money from the same crop. However, their advice did not take into account the recreational boating market and the effect E10 has on fuel storage components and the fact that E10 will separate into ethanol and unleaded petrol if exposed to moisture or condensation.

So now the boating public has reduced options on where to buy appropriate fuel, or is being forced to buy premium, high-octane unleaded petrol that really benefits only larger, high-performance outboards that were built in the past five years or so.

It has even forced many boat owners to evaluate their current fuel storage and delivery systems, in some cases leading to very expensive retrofits replacing existing components.

1 My outboard manufacturer says my engine will cope with E10, so there’s no problem?

If your outboard manufacturer confirms that your engine is built to standards required to accept E10 type fuels then you should not have any problems as far as your engine itself is concerned. But, and this is a very big but, you need to ask yourself if your boat is ready. By this we mean, do you know if the fuel tank, fuel lines, seals, primer and filter are all E10 ready? If not, find out immediately because E10 damages fibreglass and aluminium tanks and melts many of the hoses and fuel system components. These dissolved components pass through the best filters and are deposited inside engines and have been shown to destroy expensive engine components. No engine warranty will cover the sort of damage experienced from this.

2 Ethanol boosts octane, so my engine will go better and/or faster.

High-octane fuel, no matter how the octane is boosted, won’t do a thing for your engine unless it has been designed to take advantage of high octane. That means that high-octane fuels (especially E10 and higher octane unleaded, like Premium 95 and 98) usually require a high compression engine to make any difference. There certainly are engines on the market that will undoubtedly perform better with higher-octane fuel but most mainstream outboards give little advantage to the user in terms of performance or fuel economy from high-octane fuel. A fact box hereabouts looks at high-octane fuel and some engines that are designed to take advantage of it.

3 V8 racing uses ethanol so it must be great.

V8 racing was under pressure to become more environmentally responsible and converting to E85 (85% ethanol) was as much a PR exercise as it was an environmental solution. These high-performance cars now have a shorter range with more fuel stops because they don’t get the same mileage from E85 as they did from regular unleaded petrol. The same has been shown to be true for outboards running E10, because E10 has about 3% less energy than regular unleaded petrol.

4 E10 is 3c a litre cheaper, so why not buy it?

Most petrol companies charge less for E10 fuel but the difference in price between standard unleaded and E10 varies widely. Another factor to consider is that E10 has 3% less energy per litre, which gives about 3% less range. For example, if fuel is $1.40 a litre then E10 needs to be 4c a litre cheaper JUST to break even in terms of kilometres per litre obtained. You end up paying more for E10 because you use more over the long term.

5 E10 is better for the environment.

Yes, but the jury is out on that. E10 is renewable because it comes from crops and not oil fields but the energy and effort needed to make the ethanol in E10 may well outweigh the environmental benefit. There is also the impact of increased pesticide, fertiliser and other chemical use to consider, something rarely mentioned. E10 will reduce some emissions, important in crowded cities, but it uses a lot of fuel, energy and pesticides to produce – not so good for our marine and coastal environments because most of the pollutants get washed into the rivers and creeks during rain.

6 There is an additive that will fix any problems with E10.

No additive claims to fix paint peeling, melting fibreglass or phase separation of ethanol and unleaded in stored or moored boats. All the claims made by these expensive additives are necessarily vague and we suggest that the buyer beware.

7 If E10 wrecks my boat can I claim for the damages?

The Qld and NSW governments have warned against E10 use in boats. So has BP (a sticker on every pump) and others as well, along with the odd boat manufacturer. Your chances of winning a legal or insurance claim from damage caused by E10 fuel to your boat fittings or engine are next to nil – you have been adequately warned.

8 I’ve heard about phase separation. What is it and can’t I just shake up the petrol tank to remix it?

Phase separation is a most serious issue and commonly occurs when E10 fuel is left to sit idle for an extended period and moisture has entered the fuel system. Phase separation is when the ethanol and unleaded literally separate from one another in the presence of water, creating two layers of different fuels. No amount of shaking, mixing or magic additive will blend the two back together. They are like oil and water once separated.

Ethanol is heavier than unleaded petrol and sinks to the bottom of fuel tanks. This is all fine while the unleaded fuel is running through the motor, although motors will typically underperform because the octane level of the unleaded fuel is lower than it should be. Serious issues occur once the highly reactive ethanol enters the motor and is run through fuel system components such as hoses and filters that can at best cope with 10% ethanol. You think E10 is a good solvent, try almost 100% ethanol! This is why most motor manufacturers advise against using any ethanol fuel, and certainly not blended fuel that has undergone phase separation.

As I was researching this article and reading reams of interesting and frightening reports, it occurred to me that the E10 issue is much bigger than I first imagined.

A quick overview shows some alarming points that boat owners, boat manufacturers and boat users really need to get their heads around.

Starting at the top, with ethanol being such a good solvent.

The nature of ethanol means that it is a stronger solvent than ordinary fuel. This may lead to particles in your fuel storage system and fuel lines being dissolved, loosened or disturbed, allowing these particles to enter the fuel destined for your engine. At best, your fuel filter catches the dissolved particles; at worst, they make it into your engine and start to accumulate in all sorts of strange places.

Ethanol can also damage gelcoat and fibreglass around fuel intakes. The Queensland Government advises boaters to clean up ethanol blended fuels spills immediately and thoroughly!

But it gets worse. Aluminium fuel tanks and boats are at risk due to ethanol’s ability to conduct electricity. The extra conductivity of ethanol can lead to an increased risk of galvanic corrosion, reducing the structural integrity of fuel tanks and boats, and promoting unsightly corrosion blisters under paintwork, especially near the fuel inlet.

The very worst are fibreglass tanks. If they were not built to E10 standard, any ethanol will immediately start to dissolve the tank. That means a weakened tank that has the potential to fail and leak. But before then, the dissolved fibreglass chemicals, like styrene, will pass through the best of filters and coat the inside of sensitive engine components. This has led to engines being damaged beyond repair.

Some say a week is about long enough to store E10 in a warm environment. Others say two weeks, while others refuse to speculate. I work in the rec fishing industry and I can say for a fact my boat does not hit the water every week and I guess other most boats don’t, either. So the fuel is likely to go off and lose its octane rating, leading to engine pinging and underperformance.

Tips for storage of E10 include completely emptying fuel tanks or using a fuel stabiliser. So just how do you go about removing all the fuel from your in-built tank? Fuel stabilisers are great as long as the stabiliser is added to new fuel; they will not stabilise old fuel or rejuvenate old fuel.

Yet more problems arise if your tank is almost empty when stored, even for a short period, because it leaves more air space in the fuel tank for water vapour condensation to occur, leading to phase separation of the E10 fuel.

To stop phase separation it is recommended to fill the fuel tank almost to the top to reduce condensation. Fine, but then the E10 fuel will go off if left to sit for two weeks. And fuel also expands with heat, and you do not want E10 fuel leaking from the fuel vent onto your boat. A no win situation.

So is it any wonder that all fuel sellers in Australia have warnings about the use of ethanol blended fuel in boats? It’s a warning boaties should heed.

For starters, the easiest way to avoid the problems is to not use E10 fuel for your boat – ever! E10 really is a bad idea for boaties.

Failing that, and at times you may not be able to avoid E10, you should completely drain the fuel tank and mechanically clean it to remove any traces of rust or aluminium oxides and then dry it thoroughly to minimise the presence of water.

If your boat was built pre-1990, seriously consider replacing the fuel tank, fuel line and components and get a fuel filter that is at least 10-microns. And carry spare fuel filters and change them every three to six months.

Just about all outboard manufacturers recommend that a fuel stabiliser should be used (regardless of the fuel) to ensure the fuel does not lose its octane rating. A lowering of the octane rating in your boat fuel will lead to a host of problems with performance.

Several manufacturers say, though, that these fuel stabilisers will not fix phase separation or increase octane levels of old fuel and should be added only to fresh fuel.

If you must use E10 fuel, it is highly recommended to fill your tank to around 90% of its capacity, leaving as little air space as possible. It is not recommended to completely fill the tank because expansion of the fuel when heated through the day will lead to leaking from the overflow or fuel vent, exposing your fibreglass or aluminium boat to the dangerous E10 fuel. Again, another compromise you must make with E10.

So there are a few tips and tricks if you have to use E10. But make no mistake, the whole industry recommends you DO NOT USE E10 fuel for boating purposes unless you absolutely must.

I hope this has helped you make some sense of the E10 debate. Boat manufacturers, component distributors, outboard importers and distributors are all working hard to make products that will be capable of dealing with E10’s limitations in a marine environment. But not one of them can solve the big issues of phase separation and fuel going off in such a short period.