Your car or truck engine runs on power released when gas is burned during internal combustion. Your original spark plugs provide the electrical current that starts the burning. They enable starting up, and they work continually to ignite fuel and keep the car going. Without a dependable set of genuine spark plugs, your ignition system wouldn't work; you wouldn't be able to start at all. Explaining how spark plugs work starts with explaining the roles of many other engine parts. Your engine valves begin by letting a combo of air and fuel into your engine cylinders. Then, engine pistons compress the mixture. This makes more of its power available for release. Finally, your spark plugs explode the chemical bonds in the mix. This reaction forces your engine pistons back down and turns your crankshaft, which gets everything moving. Eventually, though, even high-quality factory spark plugs degrade. Plug leads corrode and widen, sparks get weaker or smaller, and engine inefficiency, misfires, and firing failures result. Worse yet, bad spark plugs can break. That can result in big-time engine cylinder damage, and engine repair is expensive. Luckily, telling when to change spark plugs is easy. Besides the fact that most spark plugs come factory-direct made of high-strength metals, withstanding millions of ignitions, many are extended life. This means they last around 100,000 miles. Look in your owner's manual for more info on spark plug lifespan. Be sure you aren't using any spark plugs beyond their mileage limitations, though. What you should get is also an easy question. The best spark plugs for any repair or replacement job are OEM. You can save on your next project and order them online, too, right here at our auto parts counter. Buy now and they'll be at your door in no time!