Thanks Joe I also had a similar incident with Auto fuel specifically Sunoco 94 octane auto fuel when I first built my KR2S. The header and wing tanks were constructed with Dow Derakane epoxy , which is supposed to be highly chemically resistant. After adding the fuel to the wing tanks the plane sat for a few days. When draining the tank sump valves, the fuel came out the consistency of HONEY! I immediately drained the wing tanks and left them open for 2 weeks to vent and harden up the epoxy lining. Luckily I did not transfer fuel to the header or run the engine so my damage was limited. The only auto fuel I used after that was Shell 91 which stated no ethanol on the pump mixed 50/50 with 100LL to minimize the lead deposits in the engine. Since 2023 Shell now blends ethanol in all fuels so I run only 100LL and add Decalin to lower the effects of lead build up on the valves in the VW2180. Auto fuel is not worth the risk in my experience. Buyer beware! Chris Gardiner KR2S 300+ hours on VW2180
Sent from my iPhone > On Dec 6, 2025, at 08:56, Joe Horton via KRnet <[email protected]> wrote: > > > Good Morning Folks, > I am sharing this story again as a warning to anyone with epoxy tanks. > On the way back from the gathering in Tennessee I think in 2011, I chased the > cold front home all day with landing multiple times to wait for it to move > ahead of me. I ended up landing somewhere south of Harrisburg PA. about 10 > min after the FBO closed and they had no self serve. A local took me to a > sonoco and I got 5 gal of 93 oct. (ya know the NAS Car racing fuel) and put > in the header tank with several galllons of 100LL that was still in the tank. > I flew for another 50 miles or so and had to call it for the night 50 miles > from home. Left early the next morning and got home and to work before 7 am. > I think that I flew again on maybe Wednesday or Thursday of the same week and > noticed a bit of roughness in the engine operation. My memory is a bit foggy > on the details of why I started to investigate but at somepoint that weekend > I looked into the header tank and the erosion of the gel coat inside the tank > was so evident. There was a line exactly where the fuel level had been when I > put the 5 gal of Sunoco in. There were glass cloth fibers exposed. I drained > and cut tank open and repaired it, but started to wonder about the epoxy that > had erroded off the inside. I tore down all the intake and aerocarb and found > a coating of the epoxy (vinyl ester) inside all the intake tubes and in the > carb. I pulled heads but it appeared that the epoxy that may have gotten to > the cobustion chamber burned with the fuel. What a mess. > This was the first time that N357CJ had seen auto fuel in the 6 or 7 > years of operations. > I did try it at an airport in South Caolina at a Corvair college with non > alcohol fuel and the engine ran so rough I drained it back out gave it to a > local and filled up with 100LL. The plane never saw any auto fuel again. Mark > L. has the plane now but to the best of my knowlege the wing tanks are still > fine and the header tank has another 14 years or so on it Total of over 20 > years now. > My current build has aluminum tanks in the wings so that should not > ever be an issue. The header tank was home built with just over 8 gal > capacity and has had fuel in it for nearly 4 years now. I do look in every so > often just for peace of mind. I for one will never take that risk again for > the sake of roughly $2 a gallon difference. > Like Larry always says "your results may vary" but I doubt it... > Joe Horton > Dr. Deans plane ready for inspection..N657CJ > > > > From: Kayak <[email protected]> > To: KRnet <[email protected]> > Cc: Kayak <[email protected]> > Date: Thursday, 4 December 2025 9:55 PM EST > Subject: KRnet> ethanol - anyone running it > > is anyone here running ordinary e10 ethanol car gas? > > just throwing out the question because almost all cars (including old ones) > are running on it, so it should be possible to accommodate it in an aircraft. > another option is to have a tank with 100ll just for cristical flight phases > like takeoff and climbout, and run the much cheaper car gas off the other > tank for the cruise phase... > > > -- > KRnet mailing list > [email protected] > https://list.krnet.org/mailman/listinfo/krnet
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