The replacement cycle of spark plugs is directly related to their material. The replacement cycle of nickel alloy spark plugs is 20000 to 30000 kilometers, nickel yttrium alloy spark plugs are 30000 kilometers, single platinum spark plugs are 40000 kilometers, double platinum spark plugs are 60000 kilometers, iridium spark plugs are 80000 kilometers, and platinum iridium alloy spark plugs can reach 100000 kilometers.

Spark plugs are key components of engines, consisting of a steel shell, central electrode, insulator, and side electrode. The lower part of the steel shell has a fine thread, which is used to fit with the spark plug hole in the cylinder head. The upper part has an outer hexagonal nut, which is used to fit the spark plug sleeve to tighten or unscrew the spark plug. The central electrode is a metal rod, with the lower end in contact with the upper end of the central electrode through a conductor glass body. The upper end of the metal rod is equipped with a wiring nut. There is a high alumina ceramic insulator between the steel shell and the central electrode, which insulates the central electrode when energized. The bottom part of the steel shell is equipped with curved side electrodes. There is a copper washer in the middle of the outer part of the steel shell.