How many spark plugs should be replaced at a time?

[DeKylie]

When replacing spark plugs in a car, it is generally recommended to replace all of them at once. Theoretically, even if you replace only one spark plug with the same brand and model, the discharge gap and resistance between the new and old spark plugs will differ. Not replacing all of them can lead to issues such as engine shaking, difficulty in acceleration, and increased fuel consumption. This is because differences in spark plugs can cause variations in ignition timing and energy, resulting in an imbalance in power among the four cylinders. Below are some tips to extend the lifespan of spark plugs: 1. Regularly drive the vehicle on highways. High-speed driving increases fuel injection, which helps clean carbon deposits in the engine cylinders and on the spark plug electrodes, restoring the spark plug's ignition efficiency and prolonging its lifespan. 2. Use high-octane gasoline periodically. High-octane gasoline has a higher octane rating and burns more completely, which also helps clean carbon deposits. It is not recommended for car owners to replace spark plugs themselves; it is best to have them replaced at a service station or repair shop.