How Often Should Spark Plugs Be Replaced in a Sedan?
2 Answers
Under normal maintenance conditions, spark plugs in a sedan should be replaced every 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine type, so it's recommended to follow the vehicle's manual. Below are some general guidelines for spark plug replacement: Platinum spark plugs should be replaced at 40,000 kilometers, standard nickel alloy spark plugs at 20,000 kilometers, and iridium spark plugs between 60,000 to 80,000 kilometers. Methods to determine if a spark plug is damaged: Remove the spark plug and inspect its appearance to assess its condition. A normal spark plug will have an insulator skirt and electrodes that appear gray-white, gray-yellow, or light brown. A properly functioning spark plug will have a reddish-brown insulator skirt, with an electrode gap between 0.8-0.9mm and no signs of electrode burn. If the spark plug is covered in oil or deposits but is otherwise undamaged, it can be cleaned and reused. If the spark plug is severely damaged, showing signs such as blistering at the tip, black streaks, cracks, or melted electrodes, the cause of the damage should be identified and resolved before replacing the spark plug. Additionally, if the spark plug appears blackened as if smoked, it may indicate the wrong heat range was selected or that the air-fuel mixture is too rich, or that oil is leaking into the combustion chamber.
I drive a regular family sedan, mainly for commuting to and from work. I remember the last time I changed the spark plugs was at around 50,000 kilometers when I noticed the car was noticeably shaky at idle and the acceleration response was slower. Later, when I took it to the shop for a check-up, the mechanic said they need to be replaced regularly, as the lifespan of standard copper spark plugs is typically between 30,000 to 50,000 kilometers. Since then, I’ve been changing them roughly every 40,000 kilometers, depending on my driving conditions: if I frequently drive on highways or often encounter city traffic congestion, they might wear out faster and need replacement sooner. If I drive less, they can last longer. Not replacing them for an extended period can lead to increased fuel consumption, difficulty starting the engine, and in severe cases, even engine damage. I recommend following the maintenance manual and adjusting based on your driving habits—it’s the most reliable approach. Don’t wait until problems arise to replace them; by then, the repair costs could be much higher.
