How Many Kilometers to Replace Spark Plugs?
2 Answers
Under normal maintenance conditions, replacement is recommended after driving 40,000 to 60,000 kilometers. However, this may vary depending on the brand and engine type, so it's advisable 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, with an electrode gap between 0.8-0.9mm and no signs of electrode burn. If the spark plug is oily or has 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, cracking, 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 the wrong heat range was selected or the mixture is too rich, with oil creeping up.
Over the years of repairing cars, I've learned that spark plug replacement isn't a rigid rule. Standard nickel alloy plugs need inspection at 30,000 km, while iridium or platinum ones can last 60,000-80,000 km. Recently encountered a BMW owner whose direct injection engine started misfiring at 50,000 km - the electrodes were completely worn down when we opened it up. Turbocharged cars wear spark plugs faster, and prolonged city stop-and-go traffic also calls for earlier replacement. Truth is, the maintenance manual gives the most accurate guidance - Japanese naturally aspirated engines typically recommend replacement at 100,000 km, while German cars have stricter requirements. The key is regular gap inspection - I've seen iridium plugs still performing well at 80,000 km, and also witnessed cheap plugs cracking at just 30,000 km.
