Higher octane fuel furns slower. That's why you loose power when you run it when you don't need it. The flame front is slowed down in high octane fuels so the flame front doesn't reach the piston before the piston is at TDC.

R+M/2 is the forumale to find the pump octane rating. This is referred to as Road Octane. It's the number on the little little yellow octane sticker on the fuel pump (at least in California.) It's (Research + Motor) / 2. Research Octane is a higher number. Motor octanes are lower octanes. It's just the way they are derived via testing. R+M/2 method of 86 = a Research Octane of about 91. Even my local dealer guys told me to run premium. They just didn't understand what the owners manual is calling for.

Higher octane fuels tend to be cleaner as they are made in smaller batches with higher quality control.

Just about all pump fuels in California run MTBE. (MTBE is a nasty carcinogen (causes cancers) and is going to be phased out.)

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Check the owners manual i think it said 87-91 unleaded