I run Ethanol-Free 91 in all my small engines two or four stroke with no problems.I only cut about 7 cords a year with the saws.I had an RX-1 Yamaha snowmobile with 4 carbs that they said you can run 87 Ethanol in it so I did.When I sold the sled the new owner said the carbs were gumbed up really bad.I also bought a new push mower in 1990 and ran every kind of gas through it and never touched the carb and it still runs.I run Stihl oil in all my 2 strokes also.I talked to alot of people that say stabilizer and sea foam work great for storage.