Posted on 8/28/2026
Spark plugs are small parts, but they have a direct effect on how well a gasoline engine starts, idles, accelerates, and burns fuel. Every time the engine runs, each plug has to create a strong spark inside the combustion chamber under heat and pressure. There is no single replacement interval for every vehicle. Some spark plugs may be due around 30,000 miles, while long-life platinum or iridium plugs can often remain in service much longer. The correct interval depends on the engine design, plug type, manufacturer schedule, and how the vehicle is used. Start With the Factory Maintenance Schedule The owner’s manual should be the first reference when deciding when to replace spark plugs. Manufacturers choose a specific plug design and replacement interval based on combustion pressure, ignition system output, engine temperature, emissions requirements, and expected service life. A naturally aspirated engine using long-life iridium plugs may have a much longer i ... read more