When should spark plugs typically be replaced?

Spark plugs are critical components in an engine, responsible for igniting the air-fuel mixture to start and run the engine effectively. The lifespan of spark plugs can vary significantly depending on the type used and the vehicle's operational conditions, but most modern vehicles utilize platinum or iridium spark plugs that are designed to last longer than traditional copper plugs.

The recommendation to replace spark plugs every 30,000 to 100,000 miles considers advancements in spark plug technology, as well as differences in engine design and driving conditions. Many manufacturers specify service intervals that fall within this range based on rigorous testing and performance standards to ensure optimal engine performance, fuel efficiency, and emissions control.

In contrast, replacing spark plugs too frequently, as suggested in some of the other options, may lead to unnecessary costs without any significant benefit. Hence, the 30,000 to 100,000 mile range is recognized as a practical guideline for maintaining engine efficiency while still allowing for effective longevity from higher-quality spark plugs.