I just bought the aforementioned used car. I go to put gas in my car and it says premium needed! I am not psyched on paying another 30 cents a gallon unless I absolutely have to!! Can I put regular gas in the car? Or medium grade? Or can I put premium in every 4th, 5th time (whatever) and regular the rest of the time...or medium grade? Anything to lower my gas cost without ruining the car/engine. Thanks for your help in this matter! Regards, Doug