Gas Station

When I was a kid there were only two, maybe three types of gasoline, regular and unleaded.  I went by the gas station today, and there were 5 different selections, although two were the same thing.  They had premium, mid-grade, regular unleaded, E-10, and (oddly enough) E-10.  Until I relocated to Oklahoma, I can't remember seeing a pump specifically for the E-10 gasoline.  As far as gasoline goes, E-10 only has 10% Ethanol added into it, and it has the same octane as regular unleaded.  

The octane number on the gas is actually the average of two octane test, the Research Octane (RON) and the Motor Octane (MON).  Both are documented in the ASTM test methods, and both use an engine that is made to knock, by adjusting the air fuel ratio.  So on the pump when you see the sticker R+M/2, that is what it is.  

Back in the days when I was cool and drove a 66 Mustang (high school), there was only one station that still sold leaded gas.  It was the Allsups, at the corner of Wilson and McGee.  Back in those days, I did not have a functioning gas gauge so I stopped in every 200 miles for fuel.