Ruthenium vs Iridium Spark Plugs: Here Is Everything You Need To Know

In the fascinating realm of precious metals, ruthenium, and iridium stand as unique and intriguing elements. As members of the platinum group of metals (PGMs), they exhibit distinctive properties that extend their value far beyond the sphere of jewelry into diverse fields like electronics, catalysis, and medicine.

Comparing these two elemental heavyweights is not just an academic exercise; it is a journey into the heart of matter and material science, uncovering the significant roles they play in our everyday lives. Prepare to dive into the depths of ruthenium and iridium – understanding their similarities, differences, uses, and future prospects.

What Does A Spark Plug Do?

A spark plug, while small in size, is a critical component in any internal combustion engine. It operates under extreme conditions, withstanding high temperatures and pressures, while performing an essential role – igniting the air-fuel mixture in the combustion chamber. The process is initiated when an electrical current is applied to the spark plug.

This electrical energy is transmitted through the plug, jumping a gap in the plug’s firing end, provided the voltage supplied to the plug is high enough. This jump results in a spark that ignites the compressed fuel-air mixture. Once ignited, the mixture combusts rapidly, pushing the piston down in the cylinder.

This action turns the crankshaft, and through a series of other components, ultimately drives the wheels of the vehicle. The spark plug, therefore, plays a pivotal role in the operation, efficiency, and performance of the engine.

What’s Ruthenium?

Ruthenium is a rare transition metal that belongs to the platinum group in the periodic table. It is an intriguing element, known for its impressive hardness, resistance to corrosion, and remarkable catalytic properties. Naturally occurring ruthenium is typically found within platinum ores and as a minor component in certain nickel ores.

Despite being one of the lesser-known members of the platinum group metals, ruthenium is increasingly recognized for its unique properties and potential applications in various fields.

Notably, it plays a vital role in electronics, the chemical industry, and even in catalytic converters in automobiles. Its role in the production of high-durability spark plugs has garnered particular attention in recent years.

The car engineer is showing new ruthenium spark plugs.

What Are The Pros Of Ruthenium Spark Plugs?

Ruthenium spark plugs are a recent development in automotive technology. They have several key advantages over traditional materials. Firstly, ruthenium is harder and denser than both platinum and iridium, giving it superior resistance to wear and erosion, thereby improving the spark plug’s longevity.

Additionally, it has a higher melting point, which translates to enhanced durability and resilience in high-heat, high-pressure environments typical of combustion engines.

Ruthenium spark plugs also boast improved ignition efficiency. They produce a more intense and focused spark, resulting in more complete combustion, better fuel efficiency, and improved engine performance.

Ruthenium spark plugs are becoming popular choices due to these characteristics, offering better longevity and performance over more traditional spark plug materials.

What’s Iridium?

Iridium is another member of the platinum group of metals, renowned for its hardness and corrosion resistance. It is one of the densest elements on earth, and it has the highest melting point of all the elements in the platinum group. Iridium is rare in the earth’s crust but can be found in meteorites in much higher concentrations.

Its unique properties make it valuable for a number of applications. Iridium’s high melting point and resistance to erosion make it ideal for use in high-temperature applications such as spark plugs in internal combustion engines. Iridium alloys are also used in various other industries, including electronics and the production of crucibles for growing crystals.

Iridium spark plugs.

What Are The Pros Of Iridium Spark Plugs?

Iridium spark plugs have long been favored for their durability and performance. The high melting point and hardness of iridium make it highly resistant to wear, extending the life of the spark plug significantly compared to traditional copper plugs.

Iridium plugs also require less voltage to spark, resulting in improved ignition efficiency. This reduced voltage requirement leads to better fuel efficiency and more reliable engine performance.

Furthermore, the small diameter of the iridium electrode allows for a more concentrated spark, which can improve combustion efficiency and engine responsiveness. Thus, iridium spark plugs have become a standard choice in many modern vehicles for their superior performance and longevity.

What’s The Difference Between Ruthenium And Iridium Spark Plugs?

Ruthenium and iridium spark plugs, while both members of the platinum group metals have some key differences.

Ruthenium spark plugs are relatively newer to the market and leverage the element’s superior hardness, density, and high melting point for increased longevity and efficiency. Ruthenium plugs can provide a more intense and focused spark for better combustion and fuel efficiency.

On the other hand, iridium spark plugs have been a popular choice for some time. They are known for their durability, given iridium’s high melting point and hardness, and they also provide excellent performance and fuel efficiency. The choice between the two often comes down to specific engine requirements and personal preference.

What Are The Cons Of Ruthenium Spark Plugs?

While ruthenium spark plugs offer several advantages, they do come with a few potential downsides. They tend to be more expensive than other types of spark plugs due to the rarity and cost of ruthenium.

Additionally, while they offer superior performance, the actual noticeable difference compared to other high-performance plugs like those made from iridium may not be significant enough to justify the higher cost for some users. Lastly, given that ruthenium spark plugs are a relatively new product, there is less long-term field data available compared to more established materials.

What Are The Cons Of Iridium Spark Plugs?

Iridium spark plugs, despite their advantages, are not without some drawbacks. Like ruthenium plugs, they tend to be more expensive than traditional spark plug materials due to the cost of iridium. They may also not provide a significant performance improvement in older engines not designed to take advantage of the properties of iridium spark plugs.

Lastly, while they are more durable than copper or platinum plugs, they can still wear down over time and will eventually need to be replaced.

Man changing spark plugs.

Ruthenium vs Iridium – Which One Should I Pick?

The choice between ruthenium and iridium spark plugs largely depends on your specific needs and budget. If you are looking for the latest in spark plug technology and are willing to pay a premium for potentially enhanced performance and longevity, ruthenium spark plugs could be the right choice.

However, if you’re seeking a tried-and-tested option that offers excellent performance and durability at a somewhat lower cost, iridium spark plugs would be a reliable choice. Always consider your vehicle’s specifications and consult with a trusted mechanic when making your decision.

Which Spark Plug Offers Better Performance?

Both ruthenium and iridium spark plugs offer superior performance compared to traditional materials like copper or platinum. They produce more reliable and efficient sparks, leading to better combustion, improved fuel efficiency, and generally more responsive engine performance.

However, ruthenium, being harder and denser, may offer a slightly more focused spark and thus potentially better combustion efficiency. This being said, the real-world performance difference between the two is likely to be minimal and may not be noticeable in most driving conditions.

Are NGK Ruthenium Spark Plugs Better Than Iridium?

NGK ruthenium spark plugs are marketed as a step up from their iridium counterparts, boasting enhanced durability and performance. However, whether they are “better” will largely depend on the specific application and your personal needs.

In terms of raw materials, ruthenium is denser and harder than iridium, which theoretically could translate into superior performance and longevity.

However, iridium plugs have been extensively tested over time and have proven to be reliable and high-performing. Both are excellent choices for high-performance spark plugs, and the difference in real-world performance might be negligible in many cases.

Old and new car park plugs on engine background.

Is Ruthenium Cheaper Than Iridium?

Ruthenium was typically cheaper than iridium on a per-gram basis. However, due to various factors like market demand, mining output, and geopolitical issues, the prices of precious metals can fluctuate. Additionally, the cost of a spark plug does not solely depend on the price of the raw material.

Other factors like manufacturing processes, research and development costs, and branding can also influence the final retail price. As such, ruthenium spark plugs are often similarly priced or even slightly more expensive than their iridium counterparts.

Other Types of Spark Plugs

1.     Copper Spark Plugs

Copper spark plugs are often regarded as the “standard” spark plug material. These plugs have a solid copper core but the electrode is tipped with nickel alloy, which is softer and less durable than platinum, iridium, or ruthenium. However, copper conducts electricity better than any other spark plug material. This superior conductivity allows for excellent spark and heat transfer, promoting efficient combustion.

Additionally, copper spark plugs are generally cheaper than their platinum or iridium counterparts, making them a popular choice for older vehicles with simpler ignition systems. On the downside, due to their softer nature, copper spark plugs typically have a shorter lifespan and require more frequent replacement.

2.     Platinum Spark Plugs

Platinum spark plugs were designed as an improvement over copper, offering better longevity due to platinum’s resistance to wear and high-temperature corrosion. They provide reliable performance and require less voltage than copper plugs to produce a spark.

However, platinum is not as conductive as copper, so the spark is not as strong. Still, for most modern vehicles, this does not create a noticeable performance difference. The cost is higher than copper but lower than iridium or ruthenium plugs.

3.     Double Platinum Spark Plugs

As the name suggests, double platinum spark plugs have a platinum disc on both the center and ground electrodes. This design extends the life of the spark plug, especially in “waste spark” ignition systems where both sides of the spark plug can fire.

The double platinum coating enhances durability and maintains a sharp edge for consistent performance over time. These plugs are more expensive than single platinum plugs, but their extended life and consistent performance can justify the additional cost.

4.     Silver Spark Plugs

Silver is the best electrical and thermal conductor of all metals, so it’s great for creating a powerful spark. Silver spark plugs feature a fine wire center electrode, enhancing starting performance and fuel efficiency. These plugs are particularly beneficial in high-performance applications where heat transfer is crucial.

However, silver is soft and these plugs may not last as long as those made from harder materials. Additionally, silver spark plugs are often more expensive than copper or platinum options.

5.     Gold Palladium Spark Plugs

While less common, gold palladium spark plugs are used in certain applications. Palladium has similar characteristics to platinum, offering good durability and performance. When alloyed with gold, it can provide excellent corrosion resistance and electrical conductivity.

Gold palladium spark plugs can offer good performance and durability, although they are not as widely used as copper, platinum, or iridium plugs. They are typically found in higher-end or specialty applications. As with other precious metal plugs, they are more expensive than traditional copper spark plugs.

How Do I Know Which Spark Plug Is Best For My Car?

Choosing the best spark plug for your car involves several factors. Firstly, consider your car’s manufacturer’s recommendations. The car manual or specification sheet will typically mention the recommended spark plug type, material, and size. Additionally, consider your driving habits and the condition of your engine.

For older or high-performance engines, a copper or silver spark plug might be best due to its superior conductivity. However, if you’re seeking longevity and better fuel efficiency, ruthenium or iridium plugs might be more suitable. Your mechanic or a trusted automotive expert can provide further guidance based on your specific needs.

How Often Should I Replace My Spark Plugs?

Spark plug replacement intervals vary depending on the material and engine type. Traditional copper spark plugs generally need replacement every 20,000-40,000 miles, while platinum and double platinum plugs can last up to 60,000-100,000 miles.

Iridium and ruthenium plugs are known for their longevity, often lasting up to 100,000 miles or more. However, always follow your vehicle manufacturer’s recommendations for maintenance schedules.

Can Use The Wrong Spark Plug Damage My Engine?

Using the wrong spark plug can potentially lead to engine damage. An improper heat range can cause poor combustion, resulting in engine misfires or overheating. A spark plug that’s too long can cause contact with the piston or valves, leading to severe engine damage. It’s crucial to always use the correct type and size of spark plug as recommended by your vehicle manufacturer.

Are Precious Metal Spark Plugs Worth The Extra Cost?

Precious metal spark plugs like those made from platinum, iridium, or ruthenium typically offer greater longevity and performance compared to traditional copper plugs. They provide better ignition efficiency, leading to improved fuel economy and overall engine performance.

If you’re seeking a long-term solution that requires less frequent replacement, investing in precious metal spark plugs might be worth the extra cost.

Can Spark Plugs Improve Performance?

High-quality spark plugs can indeed contribute to improved engine performance. They provide a stronger, more efficient spark, leading to better combustion. This results in smoother engine operation, improved fuel efficiency, and in some cases, increased power output.

However, spark plugs are just one part of an intricate engine system, and overall performance depends on the proper functioning of numerous components.

What Are The Signs Of A Failing Spark Plug?

Signs of a failing spark plug can range from subtle to obvious. You may experience issues like rough idle, difficulty starting your car, poor fuel economy, engine misfiring, or a lack of acceleration.

In some cases, the ‘Check Engine’ light may come on. If you experience any of these symptoms, it’s advisable to have your spark plugs and ignition system checked by a professional.


Whether you choose ruthenium, iridium, or any other type of spark plug, it’s crucial to understand the unique attributes each brings to your engine’s performance and longevity.

While ruthenium and iridium spark plugs offer an exciting blend of efficiency and durability, other alternatives like copper, platinum, or silver spark plugs may suit specific engines or driving conditions better.

Always align your choice with your vehicle specifications, driving habits, and budget considerations. Remember, the health of your spark plugs is integral to the smooth operation and overall performance of your vehicle. Choose wisely, and consult with an automotive professional if in doubt. Safe driving!

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About Matthew Webb

Hi, I am Matthew! I am a dedicated car nerd! During the day, I am a journalist, at night I enjoy working on my 2 project cars. I have been a car nerd all my life, and am excited to share my knowledge with you!