For 1990-2009 cars

Use premium unleaded gasoline with a posted octane of 95 ROZ or higher. In an emergency, you can use regular unleaded gasoline with an octane rating of 91 ROZ or higher. If 91 ROZ fuel is used, do not perform aggressive driving maneuvers such as wide open throttle applications. You might also hear audible spark knock during acceleration. Refill the tank with premium fuel as soon as possible to avoid damaging the engine. If you are using gasoline rated at 95 ROZ or higher and you hear heavy knocking, the engine needs service.