The spark plugs in your car's engine are indispensable. Without them, there would be no power. Despite the modern computers all new cars have, a skilled mechanic can tell volumes about the condition of your engine, the type of gas you use and your driving habits just by examining your used spark plugs. If you have a General Motors vehicle, it came from the factory with AC Delco spark plugs as original equipment. Many mechanics recommend staying with the factory brand plugs because of the tight tolerances in voltage for the onboard electronics.
Remove the spark plugs from your engine using the wrench. Set each plug aside in the order it is removed. This way you know which cylinder held which plug.
Examine the tip of each plug in a well-lit area. Compare the electrode color and condition to that on the chart (see References). AC Delco plugs wear like any other plug, so the brand on the chart is not relevant to your inspection.
Follow the recommendation on the chart for solving the problem indicated by the condition of the spark plug. Take your car to a mechanic if the trouble indicated is beyond your expertise.
