How Often Should Car Spark Plugs Be Replaced?
2 Answers
Under normal maintenance conditions, car spark plugs should be replaced after driving 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine type, so it is recommended to follow the user manual. The following standards can be referenced for maintenance and replacement: Platinum spark plugs should be replaced at 40,000 kilometers, ordinary nickel alloy spark plugs at 20,000 kilometers, and iridium spark plugs at 60,000 to 80,000 kilometers. Methods to determine if a spark plug is damaged: Remove the spark plug and observe its appearance to assess its condition. A normal spark plug's insulator skirt and electrodes should appear grayish-white, grayish-yellow, or light brown. A properly functioning spark plug has a reddish-brown insulator skirt, 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 not damaged, it can continue to be used after cleaning off the oil and deposits. If the spark plug is severely damaged—showing signs like blistering at the top, black streaks, cracks, or melted electrodes—the cause of the damage should be identified and the issue resolved before replacing the spark plug. Additionally, if the spark plug appears black as if smoked, it indicates that the wrong heat range was selected or that the air-fuel mixture is too rich, or that engine oil is leaking into the combustion chamber.
I've been driving for decades, and the frequency of changing spark plugs really varies. For my old Toyota, it felt sluggish to start every 40,000 kilometers, but after replacement, it ran smoothly. Newer cars like Hondas with platinum spark plugs can go up to 80,000 kilometers without issues. The key is driving habits—if you're always in stop-and-go traffic with short trips, they wear out faster; highway driving allows them to last longer. Symptoms like engine shaking, sudden increase in fuel consumption, or difficulty starting are signs to check them. I recommend having the mechanic inspect the spark plug gap during regular maintenance—if it's too wide, replace them to prevent unexpected stalls. Safety first. Don't delay, as poor ignition affects overall performance and can even damage the engine.
