In vehicles, just like in other mechanical components, it is the small details that matter. Tiny objects, such as spark plugs, determine the smooth-running, or otherwise, of your vehicle’s engine. It is, therefore, imperative that you change your spark plugs at regular intervals.
Just how often to change the spark plugs is a question many drivers have, and this is what we seek to answer in this comprehensive guide.
Type of Spark Plugs Used in Your Engine’s Ignition System
There are different variants of spark plugs used vehicles based on the materials used, and they determine the mileage threshold to warrant their replacement. These are regular and long life spark plugs.
Ordinary, standard, conventional, or regular spark plugs are mainly made of copper. They generally begin to wear out and need replacing around the 20,000–30,000 mile mark.
Long life spark plugs are made of materials superior in conductivity than copper, mainly platinum or iridium, and as a result, operate efficiently for more ignition cycles. Platinum spark plugs last for an average of 60,000 miles, while iridium spark plugs are the most superior of the three, with their lifespan averaging 100,000 miles.
Replace Your Spark Plugs during Maintenance
What better and convenient time to have your spark plugs replaced than during maintenance? The spark plug replacement intervals almost coincide with the maintenance intervals for most vehicles.
Two most popular mileage thresholds for general car maintenance schedules are 30K and 60K miles, which are around the same time that copper and platinum spark plugs will have begun to wear out, respectively.
For the pricier iridium spark plugs, you need not replace them during maintenance, especially if they are working properly. It is better to wait till they begin to wear out before thinking of replacing them. This helps you avoid incurring unnecessary expenses in non-essential replacements.
Diagnosing Possible Spark Plug Faults
At times, you my experience faults in your ignition system relating to the spark plugs. Like you do with other components of your car, diagnosing possible faults with your spark plugs at their onset is key to arresting the situation early enough. This saves you grievous driving inconveniences, costly repairs, bad fuel economy, and more.
Look out for these signs as possible indicators of defective spark plugs in your ignition system.
♦ You have trouble igniting your car’s engine.
♦ Your car’s fuel tank runs out a lot faster than usual.
♦ The engine is misfiring by producing unusual noise or suffers a knock.
♦ You experience slowed acceleration.
♦ Your engine backfires or after-fires.
Wrapping it up,
If followed keenly, the detailed guide we’ve provided on when to change your engine’s spark plugs will have your ignition system powering smoothly for a long time. It is also observed that newer, efficient plugs result in increased horsepower for your engine.
We advise that when replacing your spark plugs, you also change the coils/cables they combine with in the engine’s ignition system. This ensures optimal working of the ignition system when transmitting electricity.

Sam is Automole’s editor-in-chief and classic car enthusiast. Sam is studying mechanical engineering at Cockrell School of Engineering, Austin. He also writes for many top automotive publications and appears on the Collecting Cars Podcast.