spark plug

Copper vs Iridium vs Platinum Spark Plugs – Differences & Information

In General by Magnus Sellén1 Comment

spark plugSpark plugs are essential components for providing the necessary spark for ignition of the air/fuel mixture in the combustion chamber.

This is done through an electric current passed to the plugs. At the heart of the spark plugs are the side and central electrodes.

At some point, the electrodes were made from copper but this later changed to platinum or iridium. This has resulted in manufacturers making plugs from any of the materials. Choosing one can be confusing if you are not an expert.

When searching for the right spark plugs you have to consider its conductivity. Plugs need an electric current to create a spark for ignition. One of the best conductors for electricity is copper.

The main difference between these is that the copper spark plugs are performing best of them, and are not as likely to overheat as Iridium and Platinum spark plugs. Platinum spark plugs are lasting for a long period of time but have low performance. Iridium is the most expensive ones and they have a long lasting and pretty good performance.

Copper spark plugs

When it comes to electric conductivity, nothing beats copper. This has made copper spark plugs to be one of the best. Copper spark plugs have nickel alloy is used for the central electrode. Nickel alloy has the disadvantage of being soft which makes it not long lasting.

It also requires a lot of voltage for the current to flow. In this instance, older cars still use copper plugs because their electric needs are not much.

The reason most of the manufacturers will use metal at the side and center of the electrode is that copper has a low melting point. Electric current is channeled through the spark plug body and a spark is produced between the gap between the center and side electrode. If you are not sure, check the service manual for the right spark plug specifications for your engine.

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The spark is vital for the combustion of air and fuel. Using metals like platinum and iridium delays the spark and reduces chances of misfires.

Advantages of copper plugs

  • Plus are readily available and cheap
  • Plugs have a fast cooling rate that boosts performance
  • Mostly used in old version cars


  • Wear out fast at less than 20,000 miles

Iridium spark plugs

If you are looking for spark plugs that will last longer then your best bet will be the iridium plugs. Iridium is harder and more durable than copper or platinum but more expensive. In addition, the plugs are great for an electricity-hungry car because the center electrodes are small.

This means it requires less current to produce a spark. The tread has moved towards more use of iridium spark plugs.


  • The highest melting point of the plugs
  • Last longer than platinum and copper plugs


  • Most expensive of the plugs

Platinum spark plugs

The platinum plugs last longer than the copper plugs but not as much as the iridium ones. A platinum disc is melted on the tip area and this makes the plugs have a resistance for debris. The plugs are suitable for car owners with electronic distribution systems.

In addition, to the normal platinum spark plugs, we also have the double platinum spark plugs. This eliminates the probability of a waste spark.

In this instance, your platinum spark plugs will fire twice – once in the exhaust stroke cylinder and again in the compression stroke cylinder. This spark in the exhaust stroke cylinder is often wasted.


  • Long lasting can be used for up to 100,000 miles
  • They do not overheat easily

What will happen if you do not replace the spark plugs?

copper spark plugSpark plugs are vital to providing the necessary spark for ignition of fuel and air mixture. However, depending on the type of plugs you have – platinum, copper or iridium – you maybe be forced to change them sooner.

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When you are performing your routine maintenance, you change the oil filters, engine oil, fuel filters but you also check the state of your spark plugs. Plugs should be changed at intervals of between 30,000 and 50,000 miles. Iridium plugs tend to be the most long-lasting and can give you service for up to 100,000 miles.

But, when do you know that your plugs have outlived their useful purpose?  You can learn more in-depth symptoms of bad spark plugs here.

Slow acceleration

A worn out plug will not send the requisite charge to the combustion chambers. This means one of the cars combustion chambers will be not performing as usual. Most modern engines have onboard computers that regulate the current to the spark plugs. In this case, the slow acceleration could be as a result of a faulty sensor. Clogged fuel injectors or dirty air filters can also cause slow acceleration. Your mechanic can narrow down on the problem.

Engine misfiring

When you start having problems with engine misfires the culprit is often faulty spark plugs. The combustion chambers need a charge for the ignition of the fuel/air mixture which is provided by the spark plugs. Wires connected to the spark plugs could also be damaged hence not passing the right current.

When your engine starts misfiring you will notice spluttering or stumbling sounds from the engine block. This will be followed by an increase in exhaust gases and reduced mileage.

High Fuel economy

Since the fuel in the combustion chambers is not getting all ignited you will see a drop in gas mileage. Faulty spark plugs often have the gap between the side and center electrodes being too wide or small. This results in no charge being produced for combustion.

In this instance, you do not necessarily need to purchase new plugs. You can remove existing plugs and either widen or shorten the gap between the electrodes to the manufacturer’s settings.

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Problems starting the car

A good working engine should roar to life the moment you turn on the ignition switch. When your plugs are worn out you will find that you have to turn on the ignition several times before the engine starts. However, you could also be experiencing problems with your stator.

Spark plugs are not meant to last forever and should be checked for wear and tear occasionally.


Spark plugs are necessary for the effective combustion of the air/fuel mixture. For a very long time the only plugs that were available were copper spark plugs. While copper is a good conductor of heat the plugs wear out fast and need replacement after every 20,000 miles.

Platinum plugs are long lasting and eliminate the probability of a waste charge. Iridium spark plugs are the best plugs due to their durability but are costlier than the platinum and copper ones.

Hello I'm Magnus, the owner and the writer of this website. I have been working with cars since I was 16 and I'm specialized with in-depth Automotive diagnostics. Also been driving drifting for the last 6 years. I'm here to give you answers to all your automotive questions and I hope that you enjoy our content.

  1. Thank you Magnus, I would like your recommendation on spark plugs for a 2001 BMW 740il.
    Thanks much.

  2. Due to a very high demand and high ammount of comments, you have to wait for some time for your car questions to get answered. If you want to get fast answers from a certified master technician you can ask your questions here:
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