Copper vs Iridium Spark Plugs: What’s the Difference?

Routine maintenance includes spark plug replacement whenever you have a gas-powered vehicle. The spark plugs ignite the air-fuel mixture in the combustion chamber, forcing the piston downward to create power. These small devices that conduct an electrical charge down into the combustion chamber won’t last forever, and when it’s time to change the spark plugs, should you choose copper or iridium?

One of the major differences with copper vs iridium spark plugs is the price. Where copper spark plugs are usually from $3 to $8 each, iridium spark plugs are around triple the price, from $10 to $25 each. Of course, it varies depending on the model you drive.

What are the differences in these common spark plug types, and what does it mean when there’s iridium in spark plugs? Here are the answers you want.

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What Are Copper Spark Plugs?

Copper spark plugs are a type of spark plug that uses a copper core electrode in the center of the spark plug. It’s a thin rod that runs the length of the spark plug that’s surrounded in a more durable nickel alloy, and it conducts the electrical charge from the ignition coil or spark plug wire into the combustion chamber. They’ve been in use and readily available for decades.

Benefits of Copper Spark Plugs

Copper is a highly conductive material, which makes it an effective choice for the electrode in spark plugs. Copper spark plugs are generally less expensive than other types of spark plugs and are widely available. Other benefits for using copper spark plugs include:

  • They run cooler than other types of spark plugs. This is important to help control emissions such as NOx levels on older vehicles, and it prevents burning out internal components too.
  • They’re extremely dependable when they’re in good shape.
  • Cooper has a lower voltage requirement to produce a strong spark.

Disadvantages of Copper Spark Plugs

Copper spark plugs aren’t the best option for every vehicle, though. There are downsides to consider about the lowest-cost spark plugs in the range. For example, they wear out quickly compared with other options, and for many applications, copper spark plugs will need to be changed every 20,000 to 30,000 miles. They’re prone to fouling, which is when deposits build up on the electrodes that cause the spark plug to misfire or fail to fire at all. Since copper is softer than other materials used for the electrode core, it can wear out sooner.

What are Iridium Spark Plugs?

Iridium spark plugs are a type of spark plug that uses an iridium electrode in place of a traditional copper electrode. They are typically more expensive than other types of spark plugs, but they can be a good choice if you’re looking to extend the life of your spark plugs or improve the performance of your engine.

Benefits of Iridium Spark Plugs

Iridium is a very hard and durable precious metal, and it has a higher melting point than copper, making it ideal for use in spark plugs. Iridium spark plugs are known for their long lifespan and their ability to deliver a strong spark, which can help to improve the performance and efficiency of an engine.

As well, iridium is known as the most corrosion-resistant element, not just of the metals but of all elements, so it lasts longer when exposed to reactive compounds in exhaust gases.

Because of these characteristics, iridium spark plugs can be manufactured with a finer tip to concentrate the spark better without worry about premature wear or failure. Overall, you can expect iridium spark plugs to last around 100,000 miles when they’re properly paired with your vehicle’s engine. And depending on the vehicle, you might be able to improve your power and reduce fuel economy modestly with iridium plugs over copper.

Disadvantages of Iridium Spark Plugs

Of course, using a precious metal that’s much rarer than copper comes at a price. You can expect to pay around triple the price of copper spark plugs, and it doesn’t always improve how well your engine runs. And if the iridium is damaged, the benefits can be negated almost immediately.

What to Consider When Buying a Spark Plug for Your Car

When you’re shopping for spark plugs, there are a few factors to consider to ensure you’re getting parts that not only keep your car performing at its best but will maintain its reliability too.

First, consider the compatibility. Some engines can use copper spark plugs, especially older models. Many newer cars cannot operate as designed using copper-core spark plugs, and they will experience issues with dependability. Most cars that take copper spark plugs can use iridium plugs, but they need to be the right size, voltage, and heat range. Only use spark plugs that are compatible with your engine.

Performance should also be in mind. Will you get any noticeable benefits by changing up from copper to iridium? If you have a high-performance model, it’s likely worth the investment.

Maintenance cost should also factor in. Since iridium plugs are more expensive, the upfront cost is higher but they won’t need to be changed as often.

Regardless if you need copper or iridium spark plugs, you’ll find the right fit at AutoZone. Shop for all your tune-up parts, fluids, filters, and more according to your vehicle information to keep it performing at its best. If the job is too big for you, seek out one of our Preferred Shops to help you do the job.

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FAQ/People Also Ask

Are copper spark plugs better?

Copper spark plugs are the least expensive option, typically, so they’re better for a tight budget. Other options like iridium and platinum tend to last longer and perform better.

Do iridium spark plugs really make a difference?

Iridium spark plugs tend to improve acceleration and power, although modestly.

How long will copper spark plugs last?

Generally, you can expect copper spark plugs to last between 20,000 and 30,000 miles before they need to be changed.

What spark plugs are better than iridium?

Ruthenium spark plugs are available and can last even longer than iridium, but are less readily available.

Can I use copper plugs instead of iridium?

If your vehicle originally was equipped with iridium spark plugs, it’s not advised to downgrade to copper. You’ll notice loss of performance and dependability.

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