Why is there oil on the car spark plug?

[DeHazel]

Here are the reasons for oil in the spark plug: 1. The most common reason for oil stains on the spark plug is the aging of the valve cover gasket. This component is responsible for sealing the engine lubricating oil. When it ages, lubricating oil naturally appears on the spark plug. 2. Another reason could be quality issues with the spark plug (such as gap misalignment or short circuit), where oil enters through the threads, necessitating replacement with a new spark plug. However, if there is oiliness between the top of the spark plug and the electrode, it indicates oil leakage in the cylinder, which is unrelated to the spark plug. Here is some information about spark plugs: 1. The spark plug, commonly known as the "fire nozzle," functions to discharge the pulsed high voltage sent by the high-voltage wire, breaking down the air between the two electrodes of the spark plug to generate an electric spark, thereby igniting the mixed gas in the cylinder. 2. The main types of spark plugs include: standard spark plugs, insulator-protruding spark plugs, electrode-type spark plugs, seat-type spark plugs, pole-type spark plugs, and surface-jump spark plugs.