Spark plugs are an essential part of a car's ignition system. As the name suggests, they provide a spark of electricity that ignites the fuel and air mixture, and gets the engine up and running.

There's something oddly satisfying about pulling an old spark plug out of an engine, but what do you do with the plug once it's out? Maybe you're having second thoughts about changing the spark plug ...

Just like cars, lawn mower engines need their spark plugs changed on a regular basis. How often should you swap the old ones out for new ones?