Ben Visser is an aviation fuels and lubricants expert who spent 33 years with Shell Oil. He has been a private pilot since 1985.
I recently received a note from reader Scott Shroyer, who is looking to buy a used Cessna 182 with an auto gas STC. He wants to know if it is worth his time to buy the 182 “in hopes of finding auto gas at an airport to fill it up?”
A lot depends on which state Scott lives in as to the availability of auto gas without ethanol. I then forwarded his question to Todd Petersen of Petersen Aviation, who has sold more than 34,000 mogas STCs worldwide since 1983.
Scott’s question raised several questions in my mind. First, is it worth considering the fuel requirement of an engine in the purchase of an aircraft? I would say that it does at this time.
There are two advantages to an auto STC’d aircraft. One is that you can be sure that whatever happens with avgas in the future, your plane will operate on the new fuel with no modification. And two, you will be able to have some control over your fuel costs because you can always buy auto gas.
Another question concerns the future fuels debate. Why is everyone betting the entire future of general aviation on the development of an unleaded 100 octane fuel? The chance of someone developing an unleaded 100 octane fuel, and being able to market it at a price that anyone but an Arab prince can afford, is about the same as finding an 80°F day in North Dakota in January.
And why does everyone seem to think that 100 Motor octane is a magic number and that any unleaded fuel that meets this number will satisfy any aircraft engine ever built? And finally, there is this thing called liability that some people think will disappear for the common good of all mankind, if we only had an unleaded avgas. I am a realist, and I do not like the odds of this bet.
A better bet is if the GA community really got behind the use of auto fuel in LSA and STC’d aircraft and tried to increase the availability of this fuel on airports, plus work with fuel manufacturers to lower the lead level in 100LL. This would demonstrate to the EPA, et. al., that we are working at reducing the amount of lead emitted. For this to work it will require cooperation in the aviation community and some common sense by the government, but, hey, at least it has some chance of working.
I have always looked at the use of auto gas in aircraft with some caution. For it to work, it requires caution and common sense by the user. It is critical that an STC is purchased for every specific aircraft. Some people think that if one Cessna 172 can be run on auto gas, then all models of the 172 can use auto gas. Not true. If you plan on using auto gas, make sure you get the STC for your specific aircraft/engine combination, and then follow all of the limitations outlined in the STC. For example if you are doing your own refueling, you need to check for ethanol on every batch and follow the proper fuel handling procedure like your life depends on it, because it does.
Todd Petersen passed on that if you are looking for ethanol-free fuel, go to Pure-Gas.org. And if you go to StopEthanol.wordpress.com, you can sign a petition urging the EPA to eliminate ethanol from premium fuel.
You can contact Ben at Visser@GeneralAviationNews.com