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 ...

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.

So, it's time for new spark plugs. Your hands are covered in grease, you're twisting the ratchet, and –- snap. Half the spark plug stays lodged inside your cylinder head like a nonpaying tenant who ...