Re: regular or super unleaded
Keep in mind that avgas is also leaded for stability (prevents detonation or pre-ignition). Aircraft engines have much higher compression ratios than our boat motors AND two spark plugs per cylinder for a more even/effecient burn in the cylinders. It all has to do with stability and pressure (be it from atmospheric pressure or cylinder compression). ...
Um....Avgas IS leaded. But it has nothing to do with "stability"...... It has everything to do with preventing detonation in high compression and/or high HP turbo/supercharged engines.
Not ALL aviation piston engines are "Higher Compression" than our boat motors. (maybe YOUR airplane has a higher compression engine)
In Fact....MOST small aircraft piston engines are lower compression (than our boat motors) AND can run on unleaded (no-ethanol) regular grade MOGAS (the same stuff Mercury recommends running in our boats) [Hence the EAA and Peterson Autogas STC's]
Aircraft engines don't have 2 plugs per cyl for efficiency, it's for redundancy. (2 complete independent magneto ignition systems.....if one fails .......the airplane keeps flying......or a plug fouls, you don't lose 25% of your cyls in a 4cyl engine!)
Avgas doesn't 'boil' at altitude and 'vapor lock' is caused by ambient heat expanding the fuel in the lines after the pump stopped supplying pressure (i.e. shutdown after a flight). But I digress....
I don't think I said that it does.....Avgas doesn't boil at altitude, BECAUSE it has (and always had as far back as the 1950's) an RVP of around 7psi....and many aircraft fuel systems will tolerate current (non-ethanol mogas) well because it is now manufactured with a MUCH lower RVP than in the recent past.
Vapor lock can happen in any fuel system with or without a fuel pump if the engine compartment temp is high enough. It can also happen at lower temps if the engine is located at a high altitude.
Vapor lock happens when the fuel starts to boil (in the fuel line). It can also boil if the fuel line(s) fuel pump, and filter etc, are subjected to high engine compartment temps.........It's mainy why Mercury put the Cool-fuel systems in some installations.....
And yes, we BOTH digress!
And back to the premium vs regular thing.....
In the US, in areas where the gasoline MUST be oxygenated, they oxygenate all the grades not just regular. ["You People" up north are lucky to get non-oxygenated gas!!]
I think EAA would like to see non-oxygenated (non-alcohol) premium gasoline so we could use it in our airplanes. we cannot use E-10 at all because it voids the STC (supplemental type certificate) allowing mogas.......
In a boat however, aside from the fiberglass fuel tank thing), I'm with most people. I just use it. I run it mostly out by the end of the summer and replace the filter and fill it up in the spring
That little bit in the fuel line runs out while I'm warming up at the dock.
Cheers,
Rick
I always put STABIL and FRESH Non-Ox premium in the tank for storage. And I always fog the engines. I BELIEVE in storing vehicles with metal tanks FULL to avoid condensation and rust. In my boat and sno-mo's, with plastic tanks ,I store with less then 1/4 tank and fill with fresh before the 1st start when putting back into service. 
