2. Since ethanol has a higer octane than gasoline, a lower octane gasoline can be used because (at least in the US) they use an average octane level when advertising at the pump. So to have say 87 octane gasoline with 10% ethanol, 84 octane base gasoline can be used. With higher % of ethanol, lower octane base fuel can be used. Now the reason this is important is with the higher hygroscopic quality of ehtanol, the gasoline gets dilluted with water which is 0 octane. This causes 2 things. It dillutes the octane of the overall fuel approx 1% for every %of moisture absorbed into the (in this case 10%) ethanol. This results in overall lower octane. Secondly, after the ethanol abosrbs approx 0.5% water, it starts to lose its ability to bond with the gasoline molecules. This is called phase seperation. If this happens, you end up with 3 independent fluids in your tank. A layer of ethanol on top (specific gravity is approx. 0.76), followed by a layer of gasoline (SG 0.78) then at the bottom is the water that has been absorbed (SG 1.0). (Think of how oil floats on top of water in a spill). Since the pickup in the fuel tank pulls from the bottom of the tank, it is pulling the pure water into the lines. This is what leads to the corrosion issues in the steel tank and lines. Not to mention what can happen if the engine tries to compress water. In a sever case, you can end up with a hydrolock engine (admittedly so, this would be a very severe case and not the majority).
Does the fuel stabilizer that you can buy prevent the phase separation? My Dad always strongly suggests I put stabilizer in anything that's not going to be run for a couple of months. I'd planned to dump some in the bird before I stored it for the winter anyway, but I'm just curious if it's a good solution to combat the issues caused by ethanol, or if I really need to try harder to completely avoid ethanol.
