Generally, I stick with BP, (and hold my nose while doing so, considering what they did down in the Gulf...) but basically because it is a decent quality gasoline and always the lowest price per gallon where I buy fuel. If I can't get that I go for Shell....

My other car, a 1985 Mercedes 380SL seems to run the same regardless of which gas I put in it, BP, Shell or something else, and I always run a large bottle of Chevron Techron fuel system cleaner with each oil change and a large bottle of Techron Fuel Injector cleaner halfway between oil changes. That all seems to keep everything running nicely and smooth.

You can run lower octane thru a high compression engine once in awhile but if you do it all the time in the long run you will cause valve-burn and all the nastiness that goes with it...... But in a pinch you can get by, just always fill again with premium.