Spark plugs do not require any maintenance during the replacement interval. Certain level of maintenance is, however, required by the vehicle whose part the spark plugs are. All deficiencies caused by insufficient vehicle maintenance can be reflected on the spark plug. That is why we recommend, within the framework of prevention, to check the spark plugs at least once a year. Their appearance reflects technical conditions of your vehicle.
Spark plugs replacement intervals are specified for a maximum mileage performance of the engine in a good technical condition. Therefore never exceed the replacement intervals prescribed for a given type of spark plugs! Possible spark plug replacement before the interval prescribed will not cause any problem.