Thank you. Never heard to let it idle to runs dry if not going to be used for a few weeks. I typically only fill my saw half full unless I know I can run it empty with the work I have to do so that I am always adding at least some fresh the next time I use it. Plus my mix is always fresh since I run through it with my weed eater and blower all the time.
Regarding ethanol. Someone once told me 93 doesn't have ethanol in it. Is that true? I normally use 93 in my mix. However, I live near a lake people boat on and the gas station right down the road sells 89 ethanol free. Am I better running that than 93?
high octane is preferred but not required...Stihls website says 89 is OK just keep it fresh. Ethanol will screw up every fuel line and gasket in that thing so avoid it like the plague unless you like pulling your saw down to fix it all the time.
Now comes the part where your thread turns into a cage match (spoiler alert talking about oil here) the 50:1 thing is a tree hugger EPA thing....almost everyone except the diehard "Only Stihl Engineers Know type" will reccomend 40:1 with a quality oil (stihls is OK but smells like ass) the really crazy will advocate 100:1 with some super mythical synthetic oil or for the older crowds they will say 32:1 or else....40:1 works fine and splits the difference.