What type of O-Rings? Buna, EPDM, FPM (Viton), FFPM (Kalrez aka Chemraz etc.)
10% Ethanol fuels are ok to burn but shouldn't be left in for storage. I have to in my 400 gal tanks on my boat but I add blue marine grade Stabil. Rich Parker ________________________________ From: KRnet <[email protected]> on behalf of Jeff Scott via KRnet <[email protected]> Sent: Friday, December 5, 2025 10:01:07 AM To: [email protected] <[email protected]> Cc: Jeff Scott <[email protected]> Subject: Re: KRnet> ethanol - anyone running it The issue with the alcohol contaminated fuel isn't the ability for the engines to burn it, but the rapid degradation of the fuel in vented fuel tank systems. Part of the degradation is that it adsorbs waer vapor from the air and precipitates that water into the bottom of your tank compounded with alcohol from the fuel. Additionally, alcohol promotes swelling and rapid degradation of rubberized or neaprene parts in your fuel system. Regarding mogas in general, my SuperCub Clone initially had fiberglass fuel tanks constructed using epoxy resin (I know, bad idea). I ran alcohol free mogas in them for years. After I moved to Akransas, I walked into the hangar one morning and found fuel running down both sides of the plane dripping from both wings and the belly of the aircraft. Both fuel tans had suddenly suffered a rapid internal delamination with both tanks failing on the same day. I had tested the fuel and found no hint of alcohol, but there are other additives in many of today's fuels that cause swelling and degradation of rubberized, plastics, composite compounds and dissolved pipe dopes. I don't know what was in the fuel, but was able to devise a simple test for those compounds by putting a fitting with some pipe dope in the threads into the fuel and swishing it around. If the pipe dope dissolves, I wouldn't put that stuff in my tanks as almost all of our fuel systems are going to have pipe fittings with some form of pipe dope in the fittings. I did a long term soak using samples from several local gas stations with test samples of O-rings and composite layups. That same fuel from all but one local station caused swelling of O-rings, rapid destruction of composite structures, and almost instantly dissolved pipe dopes. The fuel from one local station did not react that way, nor did my control sample of 100LL. It turned out that in our area, all but one fuel station had fuel that I found to be unsuitable for use due to the fuel additives. Eventually, that station was forced by their supplier to change to the same unsuitable fuel. I have run strictly 100LL ever since. The manufacturing of 100LL meets specific standards. Local Mogas has few standards and poor controls in processing and is subject to change with no notice. As the old saying goes, your mileage may vary... -Jeff Scott Arkansas Ozarks Sent: Thursday, December 04, 2025 at 8:55 PM From: "Kayak via KRnet" <[email protected]> To: "KRnet" <[email protected]> Cc: "Kayak" <[email protected]> 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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