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Andrew Cilio
/ Mar 10 2023
Spark plugs are tiny ignition components that make a big impact—even the most powerful engines are basically lifeless hunks of metal without them. As their name implies, these little plugs create the spark that ignites the fuel and forces your engine's pistons to move, bringing your vehicle to life.
However, one size—or rather, one metal—does not fit all. Below, we'll go over the three different types of spark plugs and explain what makes them unique.
You can break spark plugs down into three types of metal: copper, platinum, and iridium. Their main differences have to do with cost and longevity, with some more prone than others to fouling (a nicer word for the gunky buildup that accumulates when they've been firing too hot).
Forget gold—copper is the standard when it comes to spark plugs. This baseline option has a copper core, but the exposed part of the center electrode that actually exchanges electricity with the ground electrode is coated in nickel alloy.
For purposes of comparison with other spark plug types, it might make more sense to call these nickel spark plugs, but that's a whole other conversation.
The center electrodes on copper spark plugs have a wide diameter, which means they require more voltage to produce a spark. And since nickel is pretty soft, these tips wear out quicker than they do on stronger types of spark plugs.
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Pros |
Cons |
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Widely used Low cost Run cool |
Short life span Not ideal for performance vehicles Not for coil-on-plug or distributorless ignition |
As you could probably guess, platinum is a step up from copper. These are essentially the same as copper spark plugs but have a platinum disc attached to the center electrode tip at the contact point between the current and the ground electrode. Since platinum is much harder than nickel and has a far higher melting point, it takes much longer for the tip to wear down.
That higher heat rating also allows them to burn off more of the carbon that builds up and causes fouling. However, since platinum burns hotter and isn't quite as good a conductor as copper, platinum spark plugs suffer a little in performance.
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Pros |
Cons |
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Moderate cost Longer life span than copper Less prone to fouling than copper |
Moderate performance Shouldn't be downgraded to copper Designed for coil-on-plug ignition |
Nope, we're not talking about the latest Billboard pickup truck hit.
Double platinum spark plugs have both a platinum disc on the center electrode and another on the ground electrode. Double platinum spark plugs are designed for waste spark systems, in which the spark travels from the center electrode to the ground electrode and back again. The waste comes from that second trip back to the center node, when there's no gas left for the spark to burn.
A notch above platinum spark plugs are iridium spark plugs, which are even longer-lasting—and more expensive. Iridium has an extremely high melting point and can be whittled down to a very fine surface and still maintain its longevity, meaning less voltage is required for the same spark.
All these qualities combine for a hyper-efficient, ultra-durable spark plug at a premium price. However, like platinum, iridium isn't as conductive as copper.
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Pros |
Cons |
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Longest-lasting Maximum efficiency Least prone to fouling |
Most expensive Less conductivity than copper Shouldn't be downgraded to either cheaper option |
Also like platinum spark plugs, iridium spark plugs come in the double variety. If your vehicle calls for double iridium, it's not recommended to downgrade to double platinum, but you may be able to upgrade from double platinum to double iridium.
So, how do these three spark plugs stack up against each other? If you've got your choice of two or three of the above, here's how they compare.
Spark plugs are the components in your engine responsible for creating the bolt of electricity that ignites the air/fuel mixture, forcing the engine's pistons to get moving in the cylinders. Most engines have one spark plug per cylinder—unless you've got a Hemi, which has two per cylinder—so if you've got a V6 or straight 6, you'll have six spark plugs.
These little lightning rods have a few important components that could help you understand how the different types of metal affect their performance. From top to bottom, you've got:
It may be time to examine your spark plugs if you notice one or more of these common symptoms:
Spark plugs generally last quite a long time, but the type of plugs you use will have a big impact on longevity. Copper spark plugs, as discussed above, have the shortest life span but can still fire reliably for up to 20,000 miles for most drivers. Iridium spark plugs, on the other hand, can go for over 100,000.
The most reliable way to figure out what kind of spark plug you need is to check your vehicle's owner's manual. For many engines, you can upgrade to a higher-quality metal, but it's never a good idea to downgrade from OEM.
Planning to jump straight from copper to iridium? Some applications might specifically require a copper spark plug or either a single or double platinum or iridium one. As with any aftermarket product, it's best not to assume anything without consulting your manual first.
Iridium spark plugs are the longest-lasting option by far, followed by platinum and then copper. However, since copper is more conductive than the other two metals, copper spark plugs have an edge when it comes to pure performance. Before you upgrade your spark plugs, be sure to check your vehicle's owner's manual to see which types are recommended.
Copper, platinum, and iridium are the most common types of spark plugs. A fourth option, silver, isn't common for vehicles in the U.S. but is sometimes used in European imports and motorcycles.
Copper spark plugs have the shortest life span and may need replacing after as few as 10,000 miles, but can last upward of 20,000. More premium options like iridium can last well over 100,000 miles. The longevity for your vehicle will depend on factors like quality of spark plug, driving style, driving conditions, and the characteristics of your particular vehicle.
A spark plug works by transferring voltage from the battery—triggered by initiating your ignition—into a small explosion of electricity inside a combustion chamber in your engine. There, a mix of air and fuel ignites, which forces a piston to move in the cylinder.
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