Jeff, I think what Dockside is going by is that “Octane” is a fuel’s ability to resist burning. The higher the octane, the more resistant it is to burn. Hence higher octane fuels used in higher compression engines to minimize spark knock or detonation. The reason for that is the higher compression increases the temperature of the air-fuel mixture. After the spark occurs, the higher temperature may cause detonation, thus the need for a fuel that resists burning prematurely at a higher temp. Having said that, it will still ALL burn providing it is of correct VOLATILITY.
Volatility is the ease to which fuel vaporizes. Gasoline droplets that do not vaporize will not burn. High volatility fuel vaporizes quickly, low volatility vaporizes slower. Gasoline must be of the correct volatility for the climate it is being used in. The engine will be hard to start and experience power loss if the volatility is too low, but will cause vapour lock if volatility is too high. Volatility is changed up seasonally when delivered to the pumps.
What octane should one use? A good start is to go with the OEM’s recommendation. In some cases you can veer from that, and in other cases you should NOT; earlier EFI is such a case, however, remember that in any EFI, data tables are used to ensure proper runability. Part of the “look-up” data is the fuel’s rating expected to be used. The computer is expecting that fuel rating to be in the tank for all the math to work. We must keep in mind however, that there are several variables that will dictate when detonation is likely to occur. Engine design and compression ratios determine octane requirements, however, requirements change with weather, driving conditions, and the mechanical condition of the engine. For example; combustion chamber deposits reduce clearance volume, in effect increasing compression and therefore fuel temperature. Reduced cooling efficiency, fuel system and ignition troubles as well as the way the owner pilots the vessel can all contribute to detonation and thus the need to tweak the octane requirements. For example, detonation is less likely to occur if there is no demand for rapid acceleration and high-speed WOT. Given the variables, everyone's individual circumstances dictate the way to go.
Hope this helps. A little long winded but I feel it’s one of those subjects that’s kind of difficult to elaborate on in just a few sentences.