Platinum vs. Iridium Spark Plugs: What's the Difference?

Both options are designed to last much longer than traditional copper spark plugs.

Connor Hoffman | 

May 3, 2024 | 3 min read

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Replacing spark plugs is one of the many regular maintenance jobs that must be done to your car, similar to an oil change or installing new brake pads and rotors. Part of the maintenance schedule in the car's owner's manual is a recommended interval for replacing your spark plugs.

For years, most spark plugs had electrodes made of copper, but those typically had a shorter life than ones made of other metals. Most newer cars use either platinum or iridium in their spark plugs, two metals that are more durable than copper, but which one should you choose for a replacement?

To help make an informed choice before changing your spark plugs, it's important to look at the differences between platinum and iridium spark plugs and how they stack up against each other.

Spark Plugs Kick-Start the Process of Getting Your Car Moving

Spark plugs are a key component of gasoline engines. When you push the starter button or twist the key, your spark plugs ignite the air-fuel mixture in your car's engine, giving energy to the pistons.

If the plugs don't ignite the combustion process, your car won't start. If they are faulty, the engine may be difficult to start and could run poorly.

As you drive, electricity from the car's battery and alternator is sent to the spark plugs through the engine's ignition coils, which significantly increase the car's 12 volts of electricity. The spark plugs ignite the air-fuel mixture inside the cylinders to continue the combustion process.

Platinum Spark Plugs Last Longer Than Copper Ones

Platinum is a harder metal than copper, which is used in most standard spark plugs. Platinum holds its shape longer, has a higher melting point, and fires hotter, which means that it also burns away deposits. All these benefits make platinum spark plugs last much longer than copper.

Iridium Spark Plugs Can Handle High Engine Temperatures

Iridium is even stronger than platinum. It shares the same benefits over copper as platinum, but it is said to be eight times stronger than platinum, and it has a higher melting point so it can handle the hottest, highest-performing engines.

Iridium Spark Plugs Are Nearly Double the Price of Platinum

It's important to first know what kind of spark plugs your car used from the factory. If it uses copper spark plugs then it's OK to upgrade to either platinum or iridium plugs when they need to be replaced.

Keep in mind that while iridium is stronger, it's nearly double the price of platinum. On the other hand, if you're hoping to save money, it's advisable not to downgrade the type of spark plugs because this can affect the performance and longevity of your vehicle.

As with most vehicle maintenance, it's smart to check the owner's manual before replacing spark plugs.

Connor Hoffman

Connor Hoffman is a writer and editor based in Kansas City. Prior to becoming a freelance writer, he was an editor at a national car magazine and worked in communications at a major automaker. He loves off-roading and camping in his 4Runner, golfing (poorly), and shredding on his mountain bike.