Lots of misinformation, myths, hear-say and error in what has been posted in some earlier comments. eg:
"Higher Octane Gas is not as volital" : gasoline volatility has nothing to do with high or low octane. Gasoline volatility (measured as RVP (Reed Vapor Pressure)) is not higher or lower on high or low octane. Gasoline volatility is adjusted by the refiners according to where/when the gasoline will be used (based on temperature)
"i think higher octane burns faster" Nope. All types of gasoline burn at the same rate, given the same ignition source.
"Octane does SLOW burning " Nope. All gasoline, regardless of the octane spec. will burn at the same speed given the same ignition source.
"Octane is an additive " Nope. Octane is not an additive. There is no such thing as "octane". It is not a product, a liquid or a magical potion. Octane (say 90 octane) is an index, a calculation. The octane calculation is made by comparing a given gasoline to a mix of isooctane and le n-heptane (both an hydrocarbon element) in a lab. engine. Two calculations are made using 2 different techniques. One is called "Research octane number", the other is called "Motor octane number". The average of the 2 gives the gasoline octane index. If a gasoline ignites with the same characteristics as a mix of say 88% isooctane and 12% n-heptane, it will be called a 88 octane number gasoline.
"you have a car with high compression higher compression, engine will require MORE Octane to maintain a "smooth flow" of the flame front. Partly true, partly not true.
The compression ratio is only one element dictating which grade of gasoline (low-mid-high octane) should be used. You can have a relatively low compression engine (say 9.5 to 1) requiring a high octane index gasoline while a much higher compression ratio (10.5 to 1) engine could be very happy running on low octane gasoline index. The spark plug location, the flame path and combustion chamber profile are important elements in defining what octane rating is required.
All gasolines (low-mid-high octane index) have basically the same BTU content. (22,500BTU/pound). As a result, all gasoline grades will give the same power and mpg if burned in similar conditions.
Bottom line: If no detonation is present with a 87 octane index gasoline, running a higher octane index gasoline is a total waste of money.
Sorry for the long post.
jackD