On Sat, Dec 6, 2025 at 3:45 PM Larry Flesner via KRnet <[email protected]>
wrote:
> That's true but the more you fly, 50 vs. 200 hours a year, the greater the
> chance of running in to bad fuel also. Many years ago, when I could trust
> the fuel, I burned nothing but auto fuel in both the Tripacer and the KR
> and both engines ran much cleaner of deposits. Once I could no longer
> trust the fuel a savings of *any amount* was no longer an option. At
> that point I simply tried to purchase the least costly 100LL I could find.
>
Larry, I can appreciate your experience of E10 fuel with ethanol and other
additives that are not appropriate for the fuel system you had built in
your planes and I thank you for warning newbs like me in making good
decisions about the fuel system parts I use. There are a lot of Rotax EAB
planes out there: Kitfoxes, RV-12s, etc. There are a lot of ULPower EAB
planes out there: RVs, Zeniths, etc. They must have made the right
decisions so they can use the cheap ("bad") auto fuel. Are they all
playing Russian roulette with their lives when they fly? Also, none of my
cars have ever had a problem with E10-87 since they outlawed MTBE and went
with ethanol as the octane booster. (I don't buy E10-91 since my cars'
engines were designed for regular unleaded with ethanol.)
I get the issue with using fuel with ethanol if the fuel system materials
are not appropriate for it. I get the issue of being aware of and properly
managing your E10 fuel storage either in the wing or in sealed containers.
If you are flying 200 hours a year and that means regularly flying about 17
hours a month, even with a standard vented wing tank, the fuel should be
consumed faster than it can degrade. If not, there are smart choices to
make it work as noted in my chat with AI in a previous post above.
I contacted ULPower and they told me the current cost to overhaul a
2000-hour TBO UL350i is $11k. Anybody want to guess what the resale value
of a run out UL350i will be in 10 years? Just for the sake of the analysis,
I will use $10k as the residual value before overhaul. Thus a $30k brand
new engine will be depreciated $20k over the 10 years. So how does that
compare to my fuel expense savings per month if I am using E10-87 at $2.50
savings per gallon over 100LL? $2.50/g x 5.5 g/hr x 17 hrs/mo = $27,500. Of
course, to do the analysis more precisely I would need to account for the
time value of money, but it likely will still show that my fuel cost
savings paid for the engine! And, of course, at your location, the
100LL-to-E10 price differential will be different from mine. In my case,
the used, overhauled O200 would have to cost me the same amount that I
could sell it for when run out again: that is, a virtually free engine.
Then I would have to decide if I prefer a brand new fully FADEC, EFI
ULPower engine or a used, overhauled old-school O200 with a lot of total
hours on the crankshaft, etc since new.
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