Is it necessary to apply silicone grease to spark plugs?

[OCaroline]

Spark plugs can be optionally coated with silicone grease, which is applied to the threaded portion of the spark plug. The purpose of applying insulating silicone grease is to provide insulation and prevent the rubber part of the high-voltage coil from conducting electricity. Spark plugs are mainly composed of a terminal nut, insulator, terminal stud, center electrode, side electrode, and shell. The main types of spark plugs include: standard spark plugs, extended insulator spark plugs, electrode spark plugs, seat spark plugs, pole spark plugs, and surface gap spark plugs. Spark plugs are installed on the side or top of the engine. Early spark plugs were connected to the distributor via ignition cables, but over the past decade or so, engines in most passenger cars have been modified to connect the ignition coil directly to the spark plug. Damaged spark plugs may exhibit the following symptoms: difficulty starting, reduced power, excessive exhaust emissions, and increased fuel consumption.