[Ghoulish Delight]

The octane rating of gasoline determines the way in which the fuel combines with oxygen during combustions, and thus the speed, violence, and temperature of the explosion (what you might call the combustion profile). A car's engine's materials, design, and timing are tuned to run ideally with a specific combustion profile determined by the grade of gasoline recommended in the owner's manual. Will using a different grade result in catostrophic damage to your engine? Hardly. But in the long run, if the engine is firing with a combustion profile outside of the design sepcs will require the engine to compensate and perhaps lead to accelerated wear or loss of peak performance.

I was very pleased to see my owner's manual recommend using only 87 octane.