No, spark plugs generally do not last 15 years; while modern iridium/platinum plugs can reach 100,000 miles, they also wear out with time, with manufacturers recommending changes every 30,000 to 100,000 miles or every 5-7 years, so leaving them for 15 years is excessive and risks engine damage from misfires and ignition system strain, even with low mileage.
Generally, its age in years is not necessarily a factor. Less-expensive copper spark plugs have a relatively short lifespan and must be replaced every 30,000 miles or less, while pricier platinum or iridium spark plugs can last up to 100,000 miles.
On average, the life of classic spark plugs is not more than 30,000 miles, and that of platinum and iridium is not more than 55,000 miles. The following are signs of malfunction that indicate the need to replace the spark plug: Deposits of ash or oil, soot, varnish or slag, melted or discolored electrodes.
Generally, spark plugs should be replaced every 30,000 to 100,000 miles, depending on the manufacturer's recommendations for your specific vehicle. Some spark plugs may need to be replaced more frequently if they are subjected to extreme conditions, such as high temperatures or extended periods of idling.
Spark plugs don't expire. Keep them in the package and don't leave them where they can fall and break or bend the tip, and it will be fine.
Overheating: Overheating can cause the spark plug's electrodes to wear out more quickly. This is often due to issues like incorrect spark plug gap, poor fuel quality, too little fuel available for combustion, or engine overheating.
Wear and tear
In our experience, spark plugs will degrade over time, much like any other part of an engine. The most common part of a spark plug to wear out and eventually fail is the electrode. This part is the narrow, tapered end where the wire connects to the spark plug.
Common Signs of Spark Plug Problems
Waiting too long can lead to engine misfires, which are often felt as jerking movements when you accelerate. Severely worn spark plugs can cause rattling or knocking sounds, affecting your engine's overall performance and leading to costly repairs if left unaddressed.
Replacing your spark plugs will help ensure your engine runs efficiently, saving you money at the pump. Another benefit of replacing your spark plugs is improved engine performance. With lousy spark plugs, you might experience misfires when they fail to ignite the air-fuel mixture.
Continuing to use a spark plug with worn electrodes puts stress on the ignition coil and can shorten its life. Please replace spark plugs sooner rather than later. Beware of only using your vehicle for short trips or slow driving! This can lead to carbon fouling or oil fouling.
Yes, a bad spark plug can cause misfires, resulting in rough running, poor performance, and engine damage. It's essential to replace faulty spark plugs promptly.
These plugs are often used in older vehicles and are more affordable but wear out quicker than other types. Platinum Spark Plugs: These can last anywhere from 60,000 to 100,000 miles, offering better performance and a longer lifespan than copper plugs. Iridium Spark Plugs: The most durable, lasting up to 100,000 miles.
Ordinary spark plugs made from copper and nickel should last 30,000 to 50,000 miles but may last as much as twice that many miles. Spark plugs made from platinum and iridium last longer. Platinum spark plugs typically last for 60,000 miles, while iridium spark plugs can last anywhere between 80,000 and 100,000 miles.
Common Problems After Replacing Spark Plugs
Car Misfiring: The engine may misfire, causing a noticeable vibration or jerking sensation. This can be a result of incorrect spark plug installation or the use of incompatible spark plugs.
How much does a spark plugs replacement cost in 2025? A typical spark plugs replacement cost in the UK is around £15 - £72. Depending on your car brand, model and engine, and whether you live in a big city or a small one, the price of a spark plugs replacement on your vehicle can be higher or lower.
Spark plug wires are usually made of flexible, heat-resistant materials like silicone or synthetic rubber, so they last as long as possible. Generally, spark plug wires need swapping every 30,000 to 70,000 miles, though they may work just fine at 100,000 miles or more.
Spark plug replacement typically costs between $100 and $250+ for a standard vehicle. This includes both parts and labor.
Bad Spark Plugs
Spark plugs convert electrical energy into a spark, which ignites your engine's fuel and air mixture – making them crucial to your engine's performance. If your spark plugs are old or faulty, they can cause fuel ignition problems and cause engine knock.
What are the signs your Spark Plugs are failing?
Older cars often had to have their spark plugs replaced every 5,000 to 10,000 miles, while some newer cars — with computer controls and more modern plugs — can go more than 100,000 miles on a set of plugs. As is often the case, the best source of service information for your vehicle is the owner's manual.
Eventually the electrodes erode away, and the gap becomes too big for the spark to jump.