Should Insulating Silicone Grease Be Applied When Changing Spark Plugs?
2 Answers
When changing spark plugs, it is recommended to apply insulating silicone grease. This is a synthetic lubricating grease with properties such as ozone resistance, high-temperature resistance, and aging resistance. It also has strong sealing capabilities, effectively preventing dust and contaminants from entering the sealed areas. Therefore, it is advisable to apply silicone grease to the white ceramic part of the spark plug to prevent electrical tracking and leakage. Spark plugs, commonly known as sparkers, function by discharging the pulsed high-voltage electricity delivered by the high-voltage wire (spark plug wire), breaking down the air between the two electrodes of the spark plug to generate an electric spark, thereby igniting the air-fuel mixture in the cylinder. The main types of spark plugs include: standard spark plugs, projected insulator spark plugs, electrode spark plugs, seat spark plugs, pole spark plugs, and surface-gap spark plugs.
Last time I helped my cousin replace the spark plugs on his Honda Civic, I specifically asked Master Li at the repair shop. He said the insulating silicone grease must be applied to the inner side of the ignition coil rubber boot and the contact area with the ceramic body of the spark plug. Applying it here prevents high-voltage leakage and rubber aging. However, be careful not to apply it to the metal threads, as it would worsen heat dissipation instead. A tiny amount of copper-based anti-seize compound (not silicone grease) can be applied to the metal threads to make future removal easier. But for high-quality spark plugs like NGK, the ceramic body actually comes with an anti-arcing coating from the factory. If you want to save trouble and install them directly, it's generally not a big issue. If you're doing it yourself, I recommend wearing gloves during the operation, as sweat on your hands touching the ceramic body might also cause leakage faults.
