How many kilometers should a Passat's spark plugs be replaced?

[HenryMarie]

Volkswagen Passat spark plugs should be replaced every 20,000 to 30,000 kilometers. Methods to determine if spark plugs are damaged: Remove the spark plugs and observe them. Judge the condition of the spark plugs based on their appearance color. Normal spark plugs have insulator skirts and electrodes that appear gray-white, gray-yellow, or light brown. Properly functioning spark plugs have insulator skirts that are reddish-brown, with an electrode gap between 0.8-0.9mm, and no signs of electrode burn. If the spark plugs are oily or have deposits but are not damaged, they can continue to be used after cleaning off the oil and deposits. If the spark plugs are severely damaged, showing signs like blistering at the top, black streaks, cracks, or melted electrodes, the cause of the damage should be identified. After troubleshooting, replace the spark plugs with new ones. Additionally, if the spark plugs appear black as if smoked, it indicates the wrong heat range was selected or the mixture is too rich, with oil creeping up.