...octane level is a way of measuring how fast the fuel burns, among other things. The important point here is that the higher the octane, the SLOWER the burn. Cheaper, lower grade gasoline burns quickly. In a high compression engine such as this, which probably has its ignition timing calibrated right up to the knock limit, engine knock (spontaneous combustion) can become a problem if the burn rate is too fast. Engine knock can be very destructive, as repeated knocking breaks down the thin insulation film of gas in the combustion chambers and surface temperatures rise. This increase in surface temperatures leads to pre-ignition, which can melt holes through pistons, etc. In engines equipped with knock sensors, ignition timing is retarded when knock is detected (which although it saves the engine before the trouble begins, it dampens performance a lot).

My advice? Put in the premium gas. Surely if you can afford a Crossfire, you can afford to spend another three dollars or less at every fill up.