The GAfuels Blog is written by two private pilots concerned about the future availability of fuels for piston-engine aircraft: Dean Billing, Sisters, Ore., an expert on autogas and ethanol, and Kent Misegades, Cary, N.C., an aerospace engineer, aviation sales rep for U-Fuel, and president of EAA1114.
Evidence of the growing interest in the use of affordable, lead-free, ethanol-free autogas, AKA, “Mogas,” in General Aviation is evidenced by Ben Visser’s recent article on the topic, The fuel of the future: Is it already here? and the results of a survey conducted by AVWeb. Further evidence is the overwhelming interest we’ve experienced to the introduction of the Aviation Fuel Club, the new Sport Fuel program, and thousands of comments on our petition calling on a ban of the blending of ethanol in Premium gasoline. There remains, however, some confusion about the pro and cons of using Mogas, something we hope to dispel below:
Myth #1 – Gasoline used in airplanes is unsafe. Fact – International standard ASTM D4814 is used for both fuel production and engine TC/STC certification. Mogas has been an FAA-approved aviation fuel since the 1980s and has had an excellent safety record.
Myth #2 – Gasoline is unstable. Fact – Modern gasoline remains stable for at least six months. Addition of some fresh fuel “rejuvenates” old Mogas. Adding ethanol to the fuel dramatically reduces its life.
Myth #3 – Gasoline is not as “clean” as 100LL. Fact – This is a problem of the past mostly eliminated through modern filters. Modern RFG (Reformulated Gasoline required in many parts of the US) is the cleanest burning gasoline made.
Myth #4 – Seasonal/regional formulations cause problems. Fact – Provided fuel remains ASTM D4814 compliant, this can be managed.
Myth #5 – Mogas is less “powerful” than 100LL. Fact – 91 octane E0 Mogas has 3%-5% more BTUs/gallon than 100LL. Lead deposits from 100LL can reduce power, though.
Myth #6 – Higher octane is always better. Fact – Only if needed for anti-detonation. Octane does not increase power. Higher octane is always more expensive, though.
Myth #7 – You can’t find ethanol-free Mogas. Fact – PURE-GAS.org lists more than 2,600 sellers across the country. The Aviation Fuel Club will help you find suppliers who deliver to airports.
Myth #8 – Gasoline producers won’t sell E0. Fact – Perhaps not at retail stations, however many fuel terminals around the country sell ethanol-free fuels to airports, marinas, farms, etc.
Myth #9 – A Mogas pump is too expensive. Fact – The Aviation Fuel Club will help find low-cost options, which might mean a small military surplus fuel trailer. U-Fuel has developed a line of smaller, self-service Sport Fuel stations ideal for GA airports wishing to add mogas.
Myth #10 – Mogas at airports costs too much and takes revenue away from airports. Fact – Mogas is typically $1-$3 cheaper than 100LL and makes its seller a profit. Airports selling mogas recoup revenue lost to self-fuelers, help sport aviation and flight schools grow, and retain the same flowage fees as 100LL sales. They also make real reductions in lead emissions, a serious public relations issue for General Aviation.
“Myth #5 – Mogas is less “powerful†than 100LL. Fact – 91 octane E0 Mogas has 3%-5% more BTUs/gallon than 100LL. Lead deposits from 100LL can reduce power, though.”
You are comparing energy content per unit quantity (BTUs / gallon) to ‘power’ ‘energy per unit time’. The 100LL will produce more power in a given engine as it explodes faster and therefore can spin the engine faster (given that the engine can be cooled and can handle the extra RPM). So myth 5 is not a myth, it is a fact.
 HIgher octanes will compress further before spontaneous combustion due to heat from high compression-IE why high performance engines require higher octane to prevent detonation; I haven’t seen anything concluding that the ‘flame front’ of the expanding gasses after ignition moves faster in a high octane fuel. Do you have anything to back up the energy per unit time argument?
Tim, no one is suggesting that mogas is a solution for those who need 100 octane fuels. But it is a good solution for 70%-80% of all legacy piston aircraft and essentially 100% of all new LSAs. To ignore affordable, lead-free mogas as an important aviation fuel is irresponsible. To deny millions of Americans whose engines in boats, power tools, old cars, airplanes, etc. can not operate with any level of ethanol is also irresponsible.
I have been flying a c-180 on floats (in sept 20 take off and landing a day) using mogas for 15years.Love it no problems 2 engines went time x.I use prem
We have used Mogas in our certified Diamond DA-20-A1 for years now. The airplane came from the factory approved for Mogas and the Rotax engine runs better on Mogas than 100LL. Use of Mogas allows the use of full synthetic oil, which prolongs engine life. We have never had any issue with the use of Mogas in several hundred hours of flying the Katana. Diamond and Rotax have both approved the use of up to E10 without limitation, although E0 is preferred.
This is all well and good for ‘sport pilots’. What about those of us who fly higher performance and turbo charged aircraft? Will ‘mogas’ work for us?
The true solution to this problem is the two companies that are developing a drop in replacement for 100LL, Swift and GAMI. The aviation industry needs to contavt their legislators and ask them to help with the development of these fuels. If we can get to the Moon and build hoover dam with our tax dillars the Feds can help with this!!!!
We have about 750,000 hours on ethanol – paying $1.50 per gallon – produces 20% more power than gas and extends my TBO from 2000 to almost 4000 hours and my Cessnas are already STC approved for ethanol. This is much safer than gas and better for the engine and much much better for the environment. This is also a big selling point to my customers because we are a Green renewable fuel. The Cessnas were just certified in the Domincan Republic to burn Rum – yes rum – at $1 per gallon. The aviation industry is going down the wrong road trying to recreate expensive gas replacement controlled by a few large corporation I can actually produce my own fuel when I want to take that next step.
Finally a good article on the advantages of Mogas. But I disagree on the difficulties of an ethanol blend, which is mostly because of the design of aviation engines and aircraft fuel systems. Every gasoline engine manufacturer or rebuilder should be producing those engines to not only operate with Mogas but also with an ethanol blend. Nothing can be done with current engines, but the aviation industry needs to prepare for the future and there are only a few in the aviation industry that are seriously doing so.
It’s the attitude of “we’ve always done it this way”, yep they have, all aircraft used to be biplanes and the engines were lubricated with Castor oil too. Not many of those flying today though.
Ethanol production is subsidized, it is done in the hope that eventually a blend of gasoline and ethanol will be cheaper and better. Whether that will transpire is in some doubt. But the aviation industry cannot afford to be caught unprepared and that has already happened with the move to unleaded fuels. The argument that ethanol deteriorates faster is invalid as there are additives and you should do preventative maintenance on all powered machinery after it has been in long term storage before placing it in service. Aircraft are not an exception.
Every manufacturer of aircraft and aviation engines using gasoline must face the fact that they must lead or their customers and their competitors will eventually demand they get out of the way.
Lead additive available at FBO’s to the small minority of high compression engines would avoid grounding excellent planes and considerably diminish lead pollution by aircraft fleet