Unless a car has a very high compression engine, it will run just fine and not hurt anything. High compression engines (or turbocharged or supercharged engines also) need gas with higher octane rating. Usually above 90. If your car normally uses high octane gas just drive it conservatively until you use up this tank and it will be fine. If your car normally uses lower octane gas (84 to 88) and you put higher octane in it there will be no change. It just costs more..