Autogas STC.

Scott Sherer

I have a few members inquiring about the auto gas STC. Here's the link: https://www.autofuelstc.com/ . Do you have this STC? What are your experiences?

rpeterson1-fly

I have had the Petersen auto fuel STC on my Cessna 182J Skyhawk since 1991. I used it regularly for the next ten to 15 years or so, often mixing/alternating with 100LL. I never used auto fuel which contained alcohol. I have never had any trouble or problems with the auto fuel or engine during that time. After a normal major overhaul in 2004, I was advised not to use auto fuel - I think because of concern for developing sticking valves- and have not used it since that time. Although it would not be my first choice, I would not hesitate using it if it became necessary. Prior to purchasing the Cessna, I also had the auto fuel STC on my Stinson 108-2 with a Franklin engine. I flew that with mostly auto fuel for about 8-10 years with no problems related to the fuel.
Reece Peterson

Scott Sherer

Thanks so much, Reece. Good to know!

Cessna64242

I owned a Grumman AA1A with a Lycoming O-235 with the EAA auto fuel STC. I flew it from 2005-2017 with no problems. In 2010 I purchased a C172M with O-320 150HP (600 hours on engine) and purchased the Peterson STC. I’ve always burned non-alcohol auto fuel with octane rating in our area of 91. My plug fouling and plug accumulation were/are dramatically reduced with auto fuel. Also oil sample trending results show extreme reduction of lead in oil sample. I don’t/can’t run auto fuel all the time due to unavailablity when traveling distances or IF I know I’m not going to be flying for several weeks. Auto fuels start breaking down after 28 days. In my other life (job) I’m a heavy duty diesel instructor for 34 years so I know the internal workings of even our antique gas aviation engines. What I’ve observed at various aviation shops, listening to experienced A&P’s and published data is 100LL is necessary for higher compression Aviation engines (octane) and necessary for valve/guide lubrication. What I’ve witnessed and have photos of disassembled O-320 valves is that over time (hours of operation) excessive lead accumulates on valve stem and starts to gully out the valve guide and/or contributes to valve sticking. So when my low compression O-320 is overhauled I will probably burn 100LL for the first 100 hours to provide initial valve guide/stem lubrication then back to non-ethanol auto fuel as per STC.

Scott Sherer

Thanks so much, I'm learning about the auto-fuel STC.