5 Types of Spark Plugs (and How to Choose the Correct Type) (2024)

Spark plugs may look the same but vary wildly in efficiency. Beyond igniting combustion, materials and sizes can alter the performance for your specific vehicle. So what may be the best spark plug for one vehicle, may be a poor choice for another.

Gone are the days of mere copper as today’s iridium, platinum and double platinum plugs last longer and require less voltage. We’ll compare all modern spark plug types so you can make the best choice when it’s time to replace them.

Spark Plug Types

When talking about different types of spark plugs, they are most commonly differentiated by material. That said, only a portion of the plug (typically just the center electrode) is made up of that material. In the case of double platinum spark plugs, the center and side electrodes use that material.

Copper Spark Plugs

This spark plug is most common and widely used on the roads today. Its core is made from solid copper, the central electrode is made from nickel alloy, and it has the largest diameter of all the other spark plugs. This means it’ll need more voltage to generate an electric current.

Nickel alloy is a soft material and lacks durability, making it a poor choice for spark plugs in modern vehicles. If you’re driving an older vehicle (1980s and earlier) with lower electrical demands, copper spark plugs are a good way to go.

Pros

• High conductivity for better spark generation
• Affordable and easily available

Cons

• Shorter lifespan (about 20-30k miles) compared to other types
• Not designed for modern, high-performance engines

Iridium Spark Plugs

When it comes to longevity, iridium spark plugs reign supreme. Made from a hard and durable metal, iridium outperforms even platinum spark plugs. While they may come with a higher price tag, the investment is worth it in the long run.

One of the reasons iridium spark plugs last so long is their small, yet dense, center electrode. This design requires less voltage to generate the electric current needed for combustion, making them a popular choice among car manufacturers.

But here’s a word of caution: if you already have iridium spark plugs installed and need to replace them, don’t downgrade to platinum or copper. If you do, you’ll likely notice a reduction in your vehicle’s performance.

Pros

• Long lifespan, typically around 80,000-100,000 miles
• Improved performance, especially for high-performance engines

Cons

• More expensive than copper spark plugs
• Can be harder to find in some auto parts stores

See Also: Spark Plug Socket Sizes and Chart

Platinum Spark Plugs

While similar in design to copper spark plugs, platinum spark plugs have a crucial difference: a platinum disc welded to the tip of their center electrode. This added feature makes platinum spark plugs more durable and long-lasting, capable of reaching over 60,000 miles on the road.

But durability isn’t the only benefit of platinum spark plugs. They also generate more heat, which helps to reduce deposit buildup and help prevent fouling. That means less maintenance and more time on the road for you.

If you’re driving a new car with an electronic distributor ignition system, platinum spark plugs are highly recommended. Their superior performance and longevity make them a smart investment for any car owner looking to get the most out of their vehicle.

Pros

• Longer lifespan than copper spark plugs, usually around 60,000-70,000 miles
• Better performance than copper, suitable for modern engines

Cons

• More expensive than copper spark plugs
• Some high-performance engines may still prefer iridium

Double Platinum Spark Plugs

If you’re driving a car with a waste spark system for its distributor ignition, double platinum spark plugs are often a good bet. This system fires the spark plugs twice, once in the compression stroke and once in the exhaust stroke. While the second spark may seem like a waste, it’s actually an important part of the system’s reliability.

The benefit of the waste spark system is that it’s not affected by environmental conditions like rain or dampness. This makes it a more reliable option for drivers who need to get where they’re going, no matter the weather.

Pros

• Increased longevity compared to single platinum, around 70,000-90,000 miles
• Improved performance for newer engine designs

Cons

• More expensive than single platinum spark plugs
• May not provide a significant improvement over iridium plugs

Silver Spark Plugs

These spark plugs have silver-tipped electrodes, providing excellent thermal conductivity. They are often used in motorcycles, race cars, and older European performance cars.

While they offer good performance, they wear down faster than platinum or iridium-tipped spark plugs and may need to be replaced more often. They conduct heat away from the combustion chamber, preventing engine damage, but may not be the best choice for engines that require long-lasting spark plugs.

Pros

• Great heat transfer characteristics for optimal engine performance
• Excellent conductivity for precise ignition

Cons

• Shorter lifespan compared to platinum and iridium plugs
• Uncommon, making them difficult to find

Factors to Consider Before Buying

Vehicle Requirements

When choosing a spark plug for your vehicle, always check your owner’s manual for specific requirements. Different vehicles have different requirements, so even though one of your cars does well with a certain plug type, it doesn’t mean you’ll get the same result with your other car.

Depending on your vehicle’s make and model, you might find recommendations for copper, platinum, or iridium spark plugs. Various automotive forums that are specific to your vehicle’s make or model are great resources when it comes to learning what car enthusiasts recommend.

Engine Performance

The type of spark plug you choose can have an impact on your engine’s performance. Copper spark plugs provide the best conductivity, while platinum and iridium offer better heat resistance. Keep in mind that the center electrode plays a significant role in the heat distribution and overall performance of the spark plug.

Longevity and Replacement

The longevity of your spark plugs is another factor to consider when making a choice. Copper spark plugs, while providing excellent engine performance, have a shorter lifespan compared to platinum and iridium spark plugs.

Copper spark plugs typically last up to 30,000 miles, while platinum and iridium spark plugs can last up to 100,000 miles. But these are not hard rules to go by. The best thing to do is periodically check the condition of your spark plugs.

Cost

While the cost of an individual spark plug may not seem like much, you need to consider that you’ll need somewhere between 4 to 8 spark plugs in almost all cases. Plan on spending anywhere from $20 to $80 for a set of spark plugs.

Spark Plug Benefits and Trade-Offs

High-Performance vs Regular Vehicles

When it comes to high-performance vehicles and motorcycles, using the right type of spark plug is critical to getting the optimal performance from your engine.

For these engines, you might consider using iridium or platinum spark plugs, as they offer better conductivity and a longer lifespan compared to copper plugs.

However, for regular commuter vehicles, copper spark plugs are often sufficient and more budget-friendly. But again, check your owner’s manual on the kind of spark plug the manufacturer recommends.

Fuel Efficiency

Ensuring fuel efficiency in your vehicle is important, and the type of spark plug you choose can have an impact. Iridium and platinum spark plugs can help improve fuel efficiency due to their ability to maintain a consistent spark over a longer period of time.

This leads to better combustion during the compression stroke of the internal combustion engine and ultimately, more efficient fuel usage.

On the other hand, copper spark plugs tend to wear out faster and may not provide the same level of fuel efficiency over their lifespan.

Emissions

Another factor to consider when choosing spark plugs is their impact onemissions. A spark plug that provides a more efficient combustion process will generally result in lower emissions. Iridium and platinum spark plugs are known for providing a more consistent spark, which can help reduce emissions in your vehicle.

Additionally, if your vehicle uses a wasted spark ignition system, double platinum spark plugs are recommended for their durability and ability to handle the demands of this type of system.

In contrast, while copper spark plugs are more affordable, they may not provide the same reduction in emissions due to their shorter lifespan and less consistent spark.