How Many Kilometers Should Spark Plugs Be Replaced?
2 Answers
Spark plug replacement cycle: Under normal maintenance conditions, they should be replaced after driving 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine, so it is recommended to follow the user manual. The following standards can be referenced for maintenance 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 color to assess its condition. A normal spark plug's insulator skirt and electrodes should appear gray-white, gray-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 contaminated with 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, with signs such as blistering at the top, black streaks, cracks, or melted electrodes, the cause of the damage should be identified. After troubleshooting, replace the spark plug with a new one. Additionally, if the spark plug appears black as if smoked, it indicates that the wrong heat range was selected or the air-fuel mixture is too rich, with oil seeping up.
When I used to work on cars, I saw plenty of spark plug issues. Generally, standard copper ones need replacement every 20,000 to 30,000 kilometers, while platinum or iridium types can last over 60,000 kilometers. If your car has been running for a while and you experience rough ignition, slow starts, or sluggish acceleration, there’s an 80% chance the spark plugs need replacing. From my experience, stop-and-go city driving wears them out faster, so it’s best to check the electrode gap around 20,000 kilometers. By the way, worn-out spark plugs hurt combustion efficiency, leading to higher fuel consumption and potential engine damage—possibly even requiring major repairs. Regular replacement is a small task; don’t wait until you’re stranded on the road. It saves money and gives peace of mind.
