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Auto Fuel STC
- Thread starter maxine_
- Start date
Raymo
Member
There isn't an "auto fuel" STC that I am aware (auto fuel includes Ethanol). Petersen, Swift Fuels and GAMI all offer STCs. the one from Petersen, if you aircraft meets requirements, allows the use of non-Ethanol fuel (aka MOGAS). The one from the other two allow the use of their specific fuels, though SwiftFuels also includes future approved fuels, if that happens.
greentips
Member
I have the Petersen STC and have used it in my C182 for 30 years without an issue. If you are in Michigan, you have to hunt a bit to find it as very few, if any, gas stations have it readily available. The EAA offers a similar one and both run about $1.50 per HP to get the STC. Some Piper PA28 variants cannot use it, while others can. I think that most non-injected, non-turbocharged Cessna airframe/engine combinations can get it.
As for my experiences, I've never had an issue with mogas on the road at airports who still offer it. Many have dropped it over the years and the airport managers I've talked to don't have a consistent or solid reason for dropping it. In Minnesota it's available everywhere at local gas stations as many boat owners, snowmobilers and aircraft owners use ETOH free 91 octane mogas. I have a friend whose mechanic told him he could just run any gas and the ETOH didn't matter. I took an some old gas cap o-rings and put it in a mason jar with 100LL for a day, a second in a jar with ETOH free 87 octane mogas, and a third in 10% ETOH mogas which tested to about 8% ethanol. The results: caliper diameter of the 100LL and ETOH free samples were identical and at the pre-test size. The 8% ETOH o-ring was about 15% larger than the other two and did not fit the gas cap, let alone seal the tank. Don't use ETOH laden fuel, no matter what the concentration is.
When I had my O470R overhauled at 1700 past its 1500 hour TBO, the engine builder called me and asked how I kept the engine so clean. I ran Phillips XC, and probably 80% of the hours on mogas. In its early days I ran AVGAS 80 until it disappeared. The current run is at 200 past TBO with good compressions, borescope inspection shows very little to no wear, oil analysis shows no significant wear metals. The first run overhaul did show wear metals which led to a more comprehensive 100 hour inspection and wear on the #5 cam lobes. The only significant change in operating procedures on the second run is I've started using Camguard about 1400 hours SMOH, so we'll see. I fly between 75 and 200 hours a year, so the airplane is flown regularly, mostly on long distance trips near maximum range (4-5) at between 4000 and 14000 ft. I've noticed no difference in burn rates or indicated airspeed rates. My engine is on the cold blooded side and runs CHTs in the low 300s to upper 290s at cruise, leaned. When 80 went away, I was burning a steady diet of 100LL and had to pull the plugs every 100 hours or so and pick the lead out of them, and thoroughly clean them to keep the engine running well. This went away with the use of mogas. I have fuel bladders replaced over 15 years ago and with more than 7000 gallons of mogas through them without a problem.
DNeuf
New member
I have run none ethanol fuel for over 20 years without a single issue in a 172A. Just make sure you test the fuel for ethanol which is easy to do. It takes two minutes. As posted above, cleaner plugs... and better for the engine than 100LL for "low compression" engines 8.5 to 1 and lower.
If there is no auto-fuel STC for your plane, I would not run it. Vapor lock issues may be a problem if your airframe does not qualify.
