Spark plugs can easily last 100,000 miles or more but it's a good idea to change the spark plugs after your vehicle reaches 100,000 miles since the last spark plug change.
When you change the spark plugs out you should also change the spark plug wires as well to increase engine performance and improve your gas mileage.
When your spark plugs are going bad you may notice poor acceleration, loss of engine power, hard starting and engine misfires.
When the engine is not getting proper spark it won't be able to burn the fuel properly and will cause a loss in engine power.
If your car is hard to start after being cold or it's hesitating or doing any of the above symptoms you need to get your spark plugs changed.