Unraveling the mysteries of fuel

Ben Visser is an aviation fuels and lubricants expert who spent 33 years with Shell Oil. He has been a private pilot since 1985.

Fuel is an item that is very important for the proper operation of our aircraft. Even though the world is full of “fuel experts,” it is still a bit of a mystery.

I recently received three questions that are actually interrelated. The first has to do with water in a plane’s fuel tank. The person changed out the fuel cap and gasket, stored the aircraft in an unheated hangar, and still found water in the fuel sump. Why? Any hydrocarbon fuel, such as 100LL, will absorb a small amount of water from the air. The amount of water suspended will depend on the temperature of the fuel. During the day, the fuel will absorb water from the air, then when it cools down at night some of the water can drop out and become free water. Because of surface area, the next day the fuel will absorb more water from the air and not the free water that had previously dropped out. The bottom line is that free water will always be present and all FBO tanks and aircraft tanks must be sumped daily or before every flight.

The second question deals with how long 100LL can be stored before being sold at an FBO. Although not specified in the ASTM D-910 spec for 100LL, the limits for the oxidation tests are designed to ensure that the fuel will be suitable for service after a year in proper storage.

There are two major concerns here. One is that not all storage is under ideal conditions. The other is turnover. At an FBO, the tanks are not usually emptied completely prior to the addition of fresh fuel, which means a part of the old fuel is left in the tank. When you consider that the fuel can sit awhile at the refinery, then at the distributor, then at the FBO, and finally in the fuel tank on an airplane, you can understand that, over time, especially if the storage is not up to par, there can be some problems with the fuel. This older fuel can allow gum formation and other problems, so it is very important that all parties who handle the fuel follow proper handling procedures and practice good inventory control.

The third question came from Bent Esbensen, who stated that the Danish government is demanding that all mogas contain at least 5% ethanol. He was wondering if this fuel would be OK to use in his plane. I understand that avgas cost $11.50 a gallon and mogas cost only $6.50 there, but the answer is still NO.

This answer is based on many factors, but the biggest is that ethanol is a polar solvent, which means that it will absorb water — and the answer to the first question tells us where the water comes from. Add the effect of aging from the second question and you have a real problem. In addition, even 5% ethanol blends will attack rubber and metal fuel system components and can cause premature failures.

So remember: Water is present in the fuel system no matter what; FBOs and other fuel systems should practice inventory and proper quality controls to ensure that avgas is sold within a year; and that ethanol is a no-no, even at the 5% level.

You can contact Ben at Visser@GeneralAviationNews.com.


  1. says

    response to Oscar 34:
    GEEEZZZ ! THAT is with 100LL fuel, where a bit of Alcohol for a short time to kill off water in the fuel doesnt hurt you too much! BUT NOTE:
    In general You always sump all tanks etc to remove water and ANY POH says that!!! Only in RARE occasions like SEVERE Cold weather Ops you may stray from that right Path!
    AND the Alcohol Product recommended like the “Prist” stuff are NOT identical to the Oxigenation BS alcohol in the carfuel!!!
    Read the books!

  2. says

    The Alcohol in the car-fuel is REALLY BAD stuff: Often the fuel only makes its octane-rating because of the alcohol present: its initial octane rating is very low, sub standart. The base stock is called BOB, like Bulk oxigenated Blendstock.
    If there is any use of car-fuel with Alcohol in it the plane its potentially deadly, in various ways.Many privately owned planes have low-powered engines of 150 HP or less that could mix unleaded premium car fuel into the 100LL with 2:1 ratio if the fuel contains NO ALCOHOL! But alcohol is extremely dangerous in aircraft and any car fuel that has any of it in it can’t be used for planes (unless they would be designed to run on pure alcohol, which would only work in the tropics). The Big Problem is: The EPA MANDATES that alcohol is put into the car fuel. If premium auto gas would be kept out of that mandate and be alcohol free, most private planes could happily supplement their lead-100LL diet with unleaded car fuel and therefore much less 100LL would be used.

    This fact makes the EPA directly responsible for a large part of the 100LL consumption and directly points out one easy and fast solution to put MUCH LESS LEAD into the air: If the EPA would mandate premium fuel to be alcohol free, much less leaded fuel would be used. It is really THAT EASY. The reduction in 100LL use by private planes would be significant.EPA needs to ban alcohol in premium gas, not lead in 100LL.

  3. Oscar says

    The anti-knock index of pure ethanol is the same as of the 115 gas. It just has to be burnt 15% more volume because of its lower calorific power, that is compensated by the compression rate that can be much increased (up to 14:1 in cars with fuel injection, maybe going to 7:1 to 10:1 in lycomings) giving more power than gas.

    That is the great advantage: Increasing the compression ratio = more power and efficiency.

  4. Oscar says

    Just look at the Cessnas POH, to see what you should add to the fuel in order to fight water in fuel … nothing less than ALCOHOL!!!!!!!!!

  5. Oscar says

    Big Bull! Alcohol do not hurt engines.
    Brazilians use 25% of alcohol in gasoline since 1976. There was no modification required, since their cars are made by Ford GM FIAT and VW mostly. They also use 92% alcohol plus 8% water (yes water, with out any gas on the tank), called 92 GL degrees, the same used to clean your house, in their cars, with minor modifications. What a waste of time to say there is prolblem with ruber, whe the rubber used in fuel system is made of sinthetic rubber like Buna-N (same used in airplanes). Just some neoprene carburator floats are supposed to get some infiltration by 92GL alcohol (with 8% water).

  6. says

    Gary Sturdy said –

    “Ethanol is required in Washington and Oregon mogas. May be increasing from 10% to 15%.”

    While Oregon is one of the few mandatory E10 states, Washington is not, quite. It has a mandatory 2% volumetric law on the books which is being completely overrun by the unintended consequences of the federal RFS mandate in EISA 2007. In Oregon we have a couple of separate exception laws passed after our disastrously stupid mandatory E10 law. As of today any supplier or station can pump ethanol free premium unleaded as long as they can find it and doing so doesn’t effect the mid-grade E10. That effectively eliminates more than 90% of the service stations in the state and there is no statutory language that guarantees a supply, nobody has to make it and by the end of next year they won’t. In Washington there is an exception to their useless law, for aviation but not for marine use. It is also passive in that there is no requirement that anyone make the product, which is the same for all state mandatory E10 laws, all five of them. The rest of the country has no protection whatsoever, not even useless exceptions for marine or aviation or small engines used in public safety.

    E15 will probably never be sold for non flex-fuel vehicles in Oregon, our mandatory E10 law only allows E10, nothing else, and we will fight any change to that law. E15 is DOA, see stopethanol.wordpress.com

    “Where in the refining process is the ethanol added?”

    Always at the terminal, not the refinery.

    “Can we as a group try to convince a refinery to produce ethanol free gas at a reasonable cost?”

    Absolutely not. The quotas in the federal RFS mandate are so onerous and so huge that the refineries are going to have to blend every drop of gasoline they produce with ethanol until the whole program implodes in 2012. The only thing you can do is urge the EPA to prohibit the blending of ethanol in premium gasoline, which they have the authority to do, or get your state legislature to pass a law prohibiting the blending of ethanol in all gasoline in the state, they have the authority too.

    If you support ethanol free premium unleaded, write the FAA and EPA, see my letter at http://www.flyunleaded.com

  7. Kent Misegades says

    Many of the questions here pertaining to ethanol and Mogas are addressed on our GAFUELS blog, http://www.generalaviationnews.com/?cat=525

    Even if your engine performs to your satisfaction now on E10, the EPA just approved E15 and its ultimate goal is to take the blend to E85. This is not a horse I’d want to hitch my wagon onto. Better is to urge the EPA to prohibit the blending of ethanol in Premium (91 octane or higher) gasoline. Our aviation alphabet groups should do their part too, as boating organizations like NMMA and BoatUS are doing on behalf of their members.

  8. Joe says

    Wow, that’s an awfully misleading article. I wish readers the best of luck in distilling (pun intended) the accurate information provided by a couple of the commenters.

    Okay, I’m annoyed enough by this guy passing himself off as an expert that I guess I’ll take the time to say the following: Ethanol doesn’t hurt metal; Ethanol won’t hurt certain modern polymers (rubbers); Ethanol saturated with water won’t magically turn into a contaminant in the carburetor of your chainsaw or your airplane; Besides incompatible rubber parts, water dropping out of suspension at colder altitudes is the real danger of running ethanol in your airplane; Automobiles enjoy more flexibility in fuel selection because modern car engines use the sort of technology that ignorant GA “experts” laughed at rather than embraced in the Mooney M20L so you’re largely stuck with ancient technology in your airplane engine (that said, I do drive a 40-yr-old car without worrying about ethanol, but I’ve replaced all the fuel lines, and my car doesn’t climb to 10,000ft).

    Joe E., P.E.

  9. Ed says

    I have an RV-4 and install fuel tanks for a living. E-10 fuel has a tendency to clean residue from fuel tanks and if there is any water in the tanks it will pull the alcohol from the fuel in what is known as phase separation. this mixture of water and alcohol will not burn and will cause corrosion in the tanks. the fuel also loses octane. Elatomers in fuel systems such as buna-n is not compatible with alcohol and will swell or deteriorate. The storage life of E-10 is also shorter and this can be a problem for aircraft, lawn mowers, snow blowers, boats etc. or any piece of equipment that sits for extended periods of time. Phase separation can occur with a little as .3% water in a tank.
    We do have a product the will mix instantly with water and will prevent phase separation. I have tested it in my fuel tank and it did not attack the pro seal of sloshing compound. A local refinery uses it when converting tanks to E-10 fuel. If anyone is interested in more information contact me @ my E-mail at edjeanne@verizon.ne with K-100 info in the subject line.

  10. John @ 8W5 says

    I believe that there is a way to use MoGas with this “Up To 10%” ethanol…….
    It will require more diligence on the pilot/owner;
    1. Do not allow the E-MoGas to sit open nor in your unsealed to air fuel tanks. Drain it if you are not going to burn it into sealed drum.
    2. If you fuel up with E-MoGas then Burn it up. BUT do not fly in the rain.
    3. Have your seals in your fuel system been changed to Viton or Nitril or Teflon material ?? Aluminum is not effected by the E-MoGas that is free of water. There is alcohol resistant rubber-like fuel hose in the Marine parts stores.

    I have tried to remove the Ethanol from MoGas & will NOT do that any more……
    I had used 33 Gallon plastic sealing drum, placed 4 gallons of tap water in them. Then went to Costco to fill them with 20 gallons of E-MoGas. After unloading the drums, I would flip them to mix the water through the E-MoGas an then allow the drum to sit for three days undisturbed. With out moving the drums I would then siphon off the water alcohol mix in the bottom………….. This is the same way that I test for alcohol so I use it to remove the alcohol………… BUT……
    After sitting a few days more there is a brownish-red thicker than the fuel liquid that appears in the bottom of the drums as well as in my plane’s fuel system sumps. I burnt about 80 gallons of that & stopped……
    If you are retired US Service & have PX rights & can get MoGas on that base, you may have your source of ethanol free MoGas. I drive 52 miles to Little Creek Indian Reservation with two 55 gallon steel drums & buy my fuel that is Regular 87 octane & cautiously drive back home. I do mix about 10% 100LL in to the MoGas before I fuel my 1956 C-172 with what I need for the planned flight with out the worry of having to defuel E-MoGas.

    So there you have what I have found from my experience of MoGas use since 1986 to present with over 2300 hours of flight time. You MUST feel OK doing this……. I have had more trouble with burning pure 100LL…. Like plug fouling, exhaust valve stem fouling/ not getting the spring pressure to set the valve & can burn the valve.

    John @ 8W5

  11. John Navratil says

    Two comments!

    (1) I run a Cessna 210 in Houston. It’s typically high-humidity (95%) with 20-degree Fahrenheit temperature swings during a 24-hour period. I sump for water before each flight and while I don’t see much of it, nor all the time, it is by no means uncommon.

    (2) The climb to 10,000 feet can see a typical temperature drop of 40-deg-F. If you are running ethanol saturated with water from that 95-degree humidity at the ground, expect for it to drop out of suspension. This is not a problem for people running chainsaws and boat motors in the ground.

  12. James Carlson says

    You’d think it’d be easy with ethanol boiling at 78.4 and isooctane boiling at 99.3. Or with ethanol dissolving nicely in water, and gasoline not so much. But the unclear part is whether you could do it in enough volume and with enough quality to bet your life on the results.

  13. Abe says

    Ethanol definitely is an aweful fuel especially if or when the vehicle is stored for any length of time. I have some antique vehicles that are stored during winters. Each spring, unless the fuel is drained and the carburetors are removed and cleaned, there is a leftover white powdery substance that gums up the works. I’ve never seen this problem before ethanol was added to the fuel. This white powdery residue also seems to cause corrosion to certain metal parts of the carburetor and unless you use newer modern gaskets, older rubber style gaskets also begin to crumble.
    Lastly, I also have experienced reduced fuel mileage using fuel that is mixed with ethanol, anywhere from 20-35% in fuel mileage.

  14. Bob Buckley says

    Gary I recently retired from a major refinery located near the Gulf coast. It is one of only a few sites left in the USA that still blends 100LL avia fuel. It is shipped all over the country. Last year there was an effort by site management to discontinue blending avgas as it is only a nich market with realitive high liability and small profit’s based on small volumns. However happy to say coporate HQ over ruled that decision.
    Auto gas blending has become very complicated over the last several years due to EPA requirments. The larger refiners have to blend several bouquet blends of auto gas depending on where it is to be sold. This is in addition to the winter blends that already require seperate blending for colder climiates. Bottom line is no refiner of any size has enough tankage to accomodate all the finished blends now required by Washington. Add to that Ethanol can not be shipped via pipeline so the refiners ship R-bob, C-bob, etc near blends which are not finished products and contain no Ethanol. The finial blending + addition of Ethanol is made at local marketing distribution terminals where the fuel trucks pick-up there products.

  15. Mike Smith says

    I am running a Superior XP 360 mostly on 91 octane automobile fuel, which is “allowed” by the engine maker. Up until 2 years ago, I could get auto fuel with MTBE instead of ethanol. The fuel I get now does have about 6-7% ethanol in it. I have been flying this engine for nearly 5 years/618 hours now with no noticable ill effects. I have never had a problem with lead fouling using auto fuel. I do live in the hot,(115F-120F & 5-10% humidity) dry, southwest so have never seen water in the fuel when I check the sumps. I have replaced all rubber fuel lines with teflon lines at the recommendation of the engine maker and I queried the carb manufacturer about parts in the carb that might be adversely affected by ethanol. They said there were none. The engine will definitely vapor-lock and QUIT when the under cowl ambient temps get high at idle on the ground (above 350F), or the auto fuel in the tanks gets hot (above 120F)and you are in a slow speed climb. I’ve had it happen once in the air turning out of the traffic pattern (before the tank fuel had a chance to cool down after sitting in the HOT SUN at 120F) and a few times on the ground waiting for takeoff clearance. My solution is to keep one tank full of Av-gas ONLY for use during extended ground ops and take-off during the summer. I use auto fuel out of the other tank for most of my cruise flying. Winter flying (high daytime temps below 75F) has not yet presented a vapor-lock problem. But I’m always ready to switch tanks if the fuel pressure gage starts to “bounce” or the engine hesitates during a critical phase of flight. That’s my story. If things keep going this way, I will have saved enough on fuel cost at 2000 hrs runout time to buy a new engine.

  16. Thomas says

    In response to the question about removal of alcohol from auto gas, I don’t there are any filters capable of separating the two. There is however a rather simple method to do so

    The test commonly used to measure the percentage of alcohol in the fuel is to remove the alcohol from a sample of the fuel, measure the volume removed, and compare it to the volume of the sample, and calculate the percentage.

    To do this you take a sample of the fuel to be tested (say 10 ounces). add to that an amount of water equal to or slightly larger than amount of alcohol that you expect to find. Shake the sample to mix the water evenly through the gasoline, and set it aside for several minutes. The water will mix with the alcohol, and that mixture will settle out at the bottom of the sample container.
    The water and alcohol at the bottom of the container will be the total volumes of both the water that you added and the alcohol that was in the gasoline. Decant the gasoline, or drain the water / alcohol mix from the bottom of the container, and you will have alcohol free gasoline left.

    If you do this on a larger scale, like a 5 or 10 gallon clear plastic container with a bottom drain, you could remove alcohol from your fuel

    A big down side to this process is that you would be dealing with large quantities of a very hazardous material. Dangers of both fire, and Haz-mat spills.

    Is is worth the trouble, and hazards ? I doubt it

    I would appreciate comments, particularly if I have overlooked any other down sides.


  17. says

    you guys sure beat the poor guy up on this subject..the short answer to the ethanol and rubber parts is the rubber lines in your 45 year cessna were never designed for the ethanol..the ruber in your honda car on the other hand was designed for ethanol so there would not be any problems how many of you that beat on this poor guy drive a 45 or 50 year old car?? the rubber problem is slow to happen but it will and not on the ground where it is just a pain …go back and reread the article one word at a time and you will understand what he is trying to tell you…ethanol in your gas will cause you more problems than you care to have maybe not today but it will be in the air for sure..those of you that use it in older planes I wish you good luck and keep the airport in sight..

  18. says

    @Gary Sturdy — In reference to Oregon mogas, there is a non-blended standard unleaded motor fuel available in once place that I know of: On boat docks. You can also buy at some marine supply stores in smaller pre-packaged containers but that’s not very practical. I’ve heard some airports might have mogas unblended but have not seen it anywhere. I heard maybe at Mulino near Portland/Oregon City, but have not looked. I run only 100LL in my plane, although it’s certified for mogas as well.

  19. Jay McIntire says

    A more important point that seems to be overlooked most of the time is the technical and economy issues. Ethanol is a cost NEGATIVE poduct. A number of technical articles have been published which highlights the FACT that it take more energy to produce it than it delivers to the final product. The octane rating is much lower and requires higher octane fuel to blend with it to achieve a final usable
    fuel. The Government decided to pay bonuses to the farmers to make it profitable to grow. The final analysis is it costs more to make than normal gasoline. Now the final blow! because Congressman who want to jump on the “Green” support list keep pushing the negative product, more farmers are joining in to grow it and there is a backlog of new construction Ethanol plants that corn is in short supply for normal cattle consumption as feed. Guess what? The price of corn has increased significantly and the growers are in a $ bananza because the Government is still paying them a bonus to grow it while the corn price escalates. Does something seem wrong in all this???

  20. says

    >> This older fuel can allow gum formation

    This is typically NOT a problem with avgas, given the inherent stability of the blend components. The more common problem with avgas is that the lighter components (butane or isopentane) weather off, leaving a fuel that doesn’t meet vapor pressure specification, and hence causes difficult cold weather starting.

    >> Is it possible to remove ethanol from (motor gasoline aka mogas)?

    In response to Charles’ question, there are folks that advise they water wash mogas to remove ethanol, and then separate the water/ethanol mixture from the gasoline. While that will remove the ethanol, it leaves you with a gasoline that’s a couple of octane numbers under whatever it was sold at (87 regular becomes 85, say…) and the wash water contains ethanol and trace amounts of gasoline, a stream that’s not readily dealt with in the environment or via sewage treatment (high biological oxygen demand).

  21. Kevin says

    I have an RC Helicopter that is powered by a 2-stroke 3Hp engine (chainsaw motor) and I must report that running auto gas with 10% ethanol is not a problem at all. In fact, I ran some 100LL avgas during the break-in period and the motor ran terrible! So the carbs must be designed to run on E10 which blows the theory out of the water (no pun intended) from small engines to big. I would also like to know what rubber specifically the Ethanol is attacking? I do not see people replacing fuel systems in automobiles that have been running E10 exclusively for many years and there are many rubber materials in automobile fuel systems. I believe California hasn’t seen Ethanol free auto gas since the early 1990’s if I’m not mistaken. Can anybody shed some light on this?

  22. John says

    This article appears to be written to the general public and is very generic in it’s terms. No mention was even made of the vapor factor. A major factor in the prohabition of ethanol in aircraft is due to the vapor factor. Ethanol tends to vaporize much more easily than 100LL and that may cause vapor locks in aircraft at altitude on a hot day. For that matter, ethanol free Mogas will vaporize more easily than 100LL but not as easily as fuel containing ethanol.

  23. jay powel says

    I have a 2005 linclon aviator and love the car a lot and have been a aircraft mechanic since 2003 and private pilot since 1996 also carry a CDL when driving an 18 wheeler we gas mileage contrubutes to the bottom line.

    Back to my Linclon Aviator with 10 percent alcohol blend at 93 octane auto fuel in texas I get 12 to 14 miles per gallon
    With 93 percent auto fuel and no alcohol I get 18 to 22 miles per gallon.
    Quick math = about 30 to a calcuulated 46 percent gain in fuel milage using the same octane and roughly the same price of fuel.

    Not counting the engine runs better on the non-blended stuff this translates to one dollar less per gallon when fuel price is at 3 dollars.

    I can easily drive 5 miles out of my way for the gas on a fillup saves me about 15 to 20 dollars.

    An I agree that 100 percent gasoline is better on all the componets in fuel system and engine

  24. Joe Scoles says

    I have read and agree with most of the arguments about ethonol in fuel as it relates to aircraft. In addition, it appears that fuel is continually taking on a bit of water. If the fuel contains Ethanol, say 10%, THEN EVERY DROP OF WATER ENTERING THAT TANK OF FUEL WILL MIX OR COMBINE WITH THE ETHANOL. This in turn increases the contamination and may even lower the octane rating; after all the Ethonol is there to raise the octane to an acceptable standard, so if we dilute this by mixing it with whatever water is present, that would introduce the secondary result of lower octane fuel which may cause detonation. We are looking at a double edged sword should we be forced to use fuel containing a percentage of ethonol in our private airplanes.

  25. Cary Alburn says

    Ben, my airplane (which is only run on Avgas) sits in an unheated hangar, and I rarely refuel it after each flight unless I plan to go out in the next day or two–usually refuel just on an “as needed” basis, since sometimes I will be taking passengers sight-seeing and can’t have full tanks and the passenger load. I dutifully sump the tanks (aluminum) and the gascolator (also aluminum) before every flight and after refueling, and as yet, I haven’t found any water or contaminants in years. When I first bought the airplane 6 1/2 years ago, I found water in the tanks, and I insisted on having the tanks cleaned out before I would take delivery, and then each tank has been cleaned out a few years ago when each of them needed to have cracks repaired near the fuel filler necks (a common problem with older Cessnas).

    So my question is this: If water is absorbed from the air and presumably also from condensation from the walls of the tanks, why have I not ever found any in my fuel? The climate here is pretty dry most of the time–does that explain it?



  26. Gary Sturdy says

    Ethanol is required in Washington and Oregon mogas. May be increasing from 10% to 15%. Where in the refining process is the ethanol added? Can we as a group try to convince a refinery to produce ethanol free gas at a reasonable cost? What kind of demand, tankage at the refinery would be required for the ethanol free gas?

  27. says

    @Kent Misegades: Yes, I do mean that gasoline for vehicles must contain 5% ethanol according to Danish legislation. Your comment on boat gas being exempt from the ethanol rule is probably valid in a large market like the US where the demand for ethanol-less gas allows this to be distributed at a profit. However, the Danish market being as small as it is – and the Danish propensity for overdoing any “environmental” idea from EU – unfortunately rules out a speciality fuel as a marketable idea.
    As for your comment on us having learned nothing from the US I can only bow my head and admit that when it comes to aviation, Europe (EASA) appears to have its head so solidly buried in its butt that it refuses to entertain the thought that anybody but Europeans knows anything about aviation.
    Kind regards
    Bent Esbensen

  28. Ron says

    What nonsense!

    Ben Visser, go argue with your wife to get your stupid little victory!

    I’ve been using ethanol mogas for over twenty years without a drop of water showing up.

    Too bad your fancy new car is full of water, according to your rationalization!

    You’re not on the dole from Shell are you?

    You’d make a great corrupt politician, too bad we can’t vote for you tomorrow!

  29. terry welander says

    I know about ethanol attacking certain rubber products. I have never heard of ethanol attacking any metal. So which metals does ethanol attack? And which metals are commonly used in ethanol fuel systems?

  30. Bob Fant says

    In response to Mr. Misegades remarks above, the term ‘mogas’ refers to automotive gasoline. So when Mr. Esbensen stated that the Danes were requiring 5% ethanol in their mogas, he was referring to automotive gasoline regardless where it might be sold.

  31. Matthew Veety says

    Thanks for the very informative article. It answered many questions I had about fuel that none seemed to have an answer to.

  32. says

    Ethanol is a huge problem in small engines as well, such as chainsaws, weed eaters, etc. The water, a contaminant in fuel, as all contaminates must be filtered out or ingested when consumed by the engine. All carburetors have small holes to regulate fuel air mixture. The smaller the engine the smaller the holes. A small contaminate in a large engine may go unnoticed, in a medium engine it may cause a falter or “burp”. That same contaminate in a small engine plugs the hole and causes a “heart attack” and requires a rebuild. Ask a small engine repair man and the will tell you that Ethanol has brought them lots of new business. Obviously no one in congressional regulation owns their own chainsaw.

  33. Kent Misegades says

    I suspect that Bent Esbensen meant that gasoline for vehicles should contain 5% ethanol, not the Mogas sold at Danish airports? Normally, gasoline for off-road vehicles (boats, airplanes, etc.) are exempted from such mandates. If he is purchasing his fuel at the local gas station, however, he’ll face the same problem as self-fuelers have experienced in the U.S. since E10 was approved. Too bad that the Danes have not learned from our miststakes with ethanol.

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