BG's Engine Clinic

Motor Moonshine - Our article on Ethanol Blended Fuels and Outdoor Power Equipment

Motor Moonshine


What's up with Ethanol?


O.E.M. Manufacturers, warranty, and Ethanol


What does Ethanol do to my lawnmower?


What if it's older gas? It looks OK, is it still good?


How can I prevent problems with ethanol?


How can I test for ethanol content in my gas?




Motor Moonshine


Motor Moonshine - That's what I like to call Ethanol Blended fuels.  - It's simply corn alcohol blended into gasoline. Too much of it, and your motor gets drunk and does funny things...  Also known as E-10, and these days, E-15, and may also be known as Ethyl Alcohol, Grain Alcohol, or just plain ol' Moonshine mixed in your gas. Whatever it is called, it can be deadly for your small engines. With the new ruling from the U.S. EPA, the formerly manageable issue of E-10 blended fuel can become a real problem of E-15 blended fuel.


Most all OEM's will have warranties that state that warranty is void if equipment is operated on fuel blends with greater than 10% ethanol. Up until October 13,2010, this was never really a problem - since the federal limit  on ethanol blends was 10%. However with the new EPA ruling, this means you will have to be even more vigilant at the pump, and watch out for any fuels that may be labeled as E-10 or E-15.


Ethanol has reduced energy potential compared to plain gas, lower boiling point than gasoline, and readily mixes with water (it is, after all, basically just fermented corn mash with the water boiled out of it).


Ethanol can cause rubber parts to swell, dry out, and break apart - fuel lines rot out from the inside (De-Lamination), carburetor parts swell up and block passages, diaphragms become porous, o-ring seals begin to distort and leak, etc.


Prevention is only possible by buying clean, fresh fuel, and do not buy more fuel than you can use in a couple months. Fuel stabilizers are available that helps keep fuel stable for longer periods, but they must be added *as soon as* the fuel is purchased.


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Properties of Ethanol fuel


Ethanol fuel as purchased at the gas pump may contain up to 15% ethanol content. Refineries may blend in ethanol to increase the octane rating to meet federal requirements and guidelines. So, for example, regular gasoline may be refined to 84 octane, and then ethanol blended in to bring the octane rating to 87. This is important to keep in mind for the rest of the article. Octane rating is a measure of how much pressure gasoline can be compressed before it spontaneously combusts. The higher the octane rating, the more pressure it can handle.


This is important to all gasoline powered engines of all kinds - when fuel is drawn in to the combustion chamber, it is then compressed, and the spark should ignite the mixture. When the octane rating is too low, the fuel - air mixture may spontaneously ignite before it is supposed to - known as detonation or pre-ignition. This can be deadly for any engine. In severe cases, prolonged detonation can punch a hole through the piston, it also contributes to overheating, and severely reduces engine power. in pull-start engines, detonation can be severe enough to literally break your fingers, hand, wrist,etc, if you have a good grip on the starter handle!  


Ethanol fuel also does not burn as well (which is why they use it to improve octane rating to begin with), it does not burn as hot, and has less volatility. It has about 30% less potential energy than gasoline alone. This results in reduced power, reduced fuel mileage - about 3% less - (funny, ain't it? - Government wants to increase mileage and then says refiners can blend fuel that reduces it!! go figure.)  In any case, this magnifies any issues your engine may have with performance - an engine that runs marginally on straight gas, may have real issues when running on ethanol blended fuel. This may result in needing more frequent tune-ups, maintenance, or even overhaul or replacement .


Ethanol also has a lower boiling point than regular gas, which can often result in vapor lock in the heat of summer, and even when engines overheat. It's a double-whammy since ethanol can contribute to engine overheating in the first place.


Replacement engines are already engineered and designed to run on up to 10% ethanol, but at this time, there are very few, if any, small engines that are designed and capable of running on fuel greater than 10% ethanol blend.


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OEM's (Original Equipment Manufacturers)


Modern engines are engineered and designed to run on modern fuels, up to 10% ethanol - The aluminum alloys, the rubber and viton gaskets, the ignition systems, pistons, rings, valves are all engineered to combat the effects of 10% ethanol. (More info on these specifics will be found as you read along..)  - However with this new ruling, which the OPEI (Outdoor Power Equipment Institute) and most all manufacturers were against, for various reasons, including insufficient testing on outdoor power equipment, even brand new equipment is vulnerable to this issue.


Using E-15 fuel in power equipment that is under warranty can, and will void the warranty.


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What Ethanol will do to your engines, even when fresh and clean


Ethanol blended fuel, if it is fresh and clean (and by fresh, we mean since the time it was blended at the refinery, not from the time you buy it at the pump!)  can safely run in most engines..


Even E-15, IF, and this is a big if - if regular, aggressive maintenance is done - fuel system cleaning and inspection, replacing the fuel lines, filters and rubber parts on a regular basis (annually or more frequently)  - This is a lot to ask for most equipment owners. 


What Ethanol does to power equipment:


  • Ethanol is Hygroscopic (absorbs water) - the combination of moisture and ethanol is highly corrosive to aluminum parts.
  • Ethanol can cause rubber parts to swell, dry out, and break apart - fuel lines rot out from the inside (De-Lamination), carburetor parts swell up and block passages, diaphragms become porous, o-ring seals begin to distort and leak, etc.


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What Ethanol will do to your engines when other things happen


Ethanol blended fuel that is no longer fresh (even if you just bought it!) can cause a multitude of issues.


When ethanol blends with enough water or moisture (as little as 0.5%) , it experiences what is called phase separation - it becomes heavier than the gas, and drops to the bottom of your fuel tank or carburetor. with most power equipment, that often results in no-start because it's suddenly trying to run on a mixture of water and alcohol, instead of gasoline. Good thing- it would ruin your engine otherwise.


One of the indicators that your fuel is absorbing water is easy to see - as ethanol absorbs moisture, the gas becomes hazy and cloudy, until there is enough water absorbed for phase separation. Using this little fact you can tell if gas contains ethanol by taking a gas sample and adding a little water, shake it up and either gas becomes hazy after the bubbles settle, or you have a thicker water line at the bottom of the sample than you started with (because it has phase separated, and dropped to the bottom - thats how the testers work).


Even without that, phase separation is a nasty thing -  remember when I explained above how ethanaol boosts octane rating? Well, with the ethanol separated from the 87 octane gas, you're now running on 84 octane fuel, and an engine with even some age can experience detonation and performance problems. - this is one reason why manufacturers will void the warranty on power equipment when it is run on fuel with greater than 10% ethanol content.


Specific to 2-cycle engines, this is even worse news- as mentioned before, water or moisture absorbed into the gas results in phase separation. When this happens it also sucks down the mix oil as well, so if you were to fill up your chainsaw with gas, use it a little bit, and then let it set long enough, if phase separation occurs and takes the oil with it, even if  you shake up the gas before you start it, chances are good that your 2-cycle equipment will be running on what is basically straight gas, resulting in severe engine damage, and very expensive repairs! (Note: you can test 2-cycle gas in the tester, and the results you see will be eye-opening!)  Most high quality 2-cycle oils nowadays contain fuel stabilizers, however.


Because ethanol does not burn as well, and yet the fuel system delivers the same amount of fuel, your engine will tend to run a bit "lean", and this is often a cause of engine overheating, which results in premature wear on all the parts, valve burning, spark plug life is shortened, and often causes blown head gaskets. (overheated aluminum expands and "squishes" the gasket beyond its recovery limit, so the next time it runs, the gasket does not seal completely, allowing combustion gasses to burn through the gasket)


This can also be a problem in cars and 4-wheelers, and even some higher end small engines - these may be equipped with oxygen sensors, and the extra ethanol burned can "fool" the oxygen sensor (O2 sensor) into thinking there's more oxygen present in the exhaust, which makes the control computer think the engine is running rich. When this happens, the control computer commands the fuel delivery (injectors) system to inject less fuel, causing a lean running condition as noted above - if your engine hesitates on acceleration, or "gallops", this can be one of the causes (Other causes include dirty or plugged fuel passages in carburetor, and air leaks around gaskets and o-rings all of which can be caused by, or contributed to by, ethanol blended fuel)


Another issue that can occur is with equipment that has electric fuel pumps - Since ethanol conducts electricity better than gasoline, this can contribute to a condition known as electrolysis when the fuel pump is running - basically the same chemical reaction that occurs in a battery - tiny atoms from aluminum may come off and attach to copper parts, or bits of copper corrode off and attach to steel parts, in a nutshell - electroplating. When the fuel pump is not running, but electrical current is present (key on, engine off, for example) there can be galvanic reaction occuring - its a reaction between dissimilar metals resulting in sand-like, powdery deposits forming - basically aluminum corrosion, but it affects other metals as well - which can plug up your fuel filters, carburetor passages, etc.


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Prevention of Ethanol Problems


Preventing problems with modern ethanol blended fuel is not too difficult. for some people they may never experience problems, since they already don't buy more gas than they use in a month or so, they take care to keep it in a clean, sealed gas can, avoiding moisture absorption.  For other people, it may require some changes to their gas buying habits - buy less gas, more frequently, and buy from a busy gas station (one that gets fresh shipments every week or so, or more often, is ideal). If you don't want to buy less gas more often, then you really need to invest in some fuel stabilizers . Do not use dry gas - it contains alcohol too. Dry Gas is actually a brand name, and generically is known as gas line anti-freeze - read the bottle label - if it says isopropyl alcohol or ethyl alcohol (in fact, any type of alcohol) you should not use it.  Buy fresh gas and immediately add fuel stabilizer.


Fresh ethanol blended fuel remains stable roughly 45 to 60 days in summertime, but as it degrades, initially the more volatile parts of the fuel will evaporate first (which can cause harder-to-start engines), followed by the less volatile hydrocarbon compunds (the "meat" of the gas) to oxidize into other chemicals (Varnish, Gum, etc) - your fuel starts to become dark and cloudy and you may begin to notice a very distinctive, very strong varnish-like odor in the gas. When it gets this bad, an engine is almost impossible to start, and any burned fuel coming from the exhaust will have that strong, distinctive varnish-y odor to it.


Fuel stabilizer is not a magic bullet - if you add it to old, stale gas, you just end up with old, stale gas that stays old and stale much longer! It will not magically make "bad" gas good again.


Fuel should be stored in D.O.T or E.P.A. approved gasoline containers and keep the caps on tightly. Store fuel in a cool, dry place. If you store it in your garage, keep the containers out of sunlight - The sun warms the fuel, causing it to expand, and the gas cans will "vent" the pressure.. When it cools down, it draws in moisture-laden air, and condensation forms on the walls of the fuel can, which, obviously, is moisture that gets absorbed by any ethanol present in the fuel.


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Testing for Ethanol content


 So, how can you tell if gas has ethanol blended into it? Short of sending samples to a laboratory (expensive) , the only other way is to use an alcohol content tester. With this simple tester, you add water to the fill line, then fill the tester the rest of the way with gas, shake it up good, and leave it to settle for 10 minutes or so. When you check again, you may note the water line is raised. this means the alchohol has mixed with water and phase separated to the bottom. The fuel tester will have a 10% line which, if the water line is up to or above that line, you've got fuel with greater than 10% ethanol.


Best advice in that case is to take the gas to an oil collection facility for disposal.  (dont just dump it out! it's bad for the environment, and it is also illegal.. it'll also burn brown patches into your lawn if you happen to dump it there.) Another alternative, if you use a bit of Drygas, and it stays clean, you can dump it in your car's fuel tank and it'll probably work just fine, as it'll mix in and blend with your existing fuel. Dry Gas is usually fine for cars, but again, it is deadly poison for small engines!


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Written by Brian Gustin — September 29, 2014

At Last! Finally, a new , working "home" for our website.

After several years managing and hosting our own web store and server, the time came we needed to start looking for a less labor-intensive shopping cart and web site management. Several "trial periods" later on various software platforms, we've finally managed to settle on one that seems to be doing exactly what we need it to do, complete with the necessary security and features we've been looking for.

We're still learning our way around the new software, but it is far easier to manage, and appears to be quite problem-free.


I've been somewhat tempted to blog about each of the software solutions we've tried, but have not had time to really reflect on them to date - suffice it to say, the one that we *thought* might be "The One" turned out to be an embarrassing FLOP!  Things were nearly ready and we'd expected to launch a month ago today, but each step of the way seemed to be met by more problems, bugs, errors, and outright "It don't work".. We almost had it fixed and sent out an announcement to our old mailing list (which no longer exists - you'll need to re-subscribe to this one!)  and set it to go live - only to discover yet another issue with the software (It wasn't recording orders properly!) .. So, over the weekend, I went back and took a fresh look at this software we are running now, and decided to give it another trial, and in a matter of 2 days, things are *almost* ready to go! - I still have a few pages to add, and a whole bunch (well over 2500) of new images to put up.. But, for the most part, we are back in action, and planning to turn it live on October 1st!


Look forward to fresh content, new changes, and we'll be trying to blog more often as well!

To our past customers that are returning  - THANK YOU! We'd not have made it this far without your support! We hope to return the favor and make sure you get what you need to keep your equipment running!




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Motor Moonshine - Our article on Ethanol Blended Fuels and Outdoor Power Equipment

Motor Moonshine   What's up with Ethanol?   O.E.M. Manufacturers, warranty, and Ethanol   What does Ethanol do to my lawnmower?   What if it's older gas? It looks OK,...

At Last! Finally, a new , working "home" for our website.

After several years managing and hosting our own web store and server, the time came we needed to start looking for a less labor-intensive shopping cart and web site management....

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