What Kind of Spark Plug Should I Buy?

Spark plugs are a key component to your engine and come in four basic varieties: copper, platinum, double platinum and iridium.

The most important detail in a spark plug is matching your engine’s design. Copper has high conductivity and low price, but also a shorter lifespan. Harder platinum and iridium plugs cost a little more and tend to last longer, but the best fit is always the one designed for your engine.

You need the metal in the spark plug to meet your vehicle’s needs, so stick with your owner’s manual recommendation for the best performance. If you don’t have an owner’s manual, you can always consult with your local AutoZone store.

Different Kinds of Spark Plugs


Copper Spark Plugs

Copper plugs have a solid copper core with a nickel alloy electrode. Nickel is softer than platinum or iridium, and has a shorter life. These plugs are usually best for older, low-voltage systems. Because of copper's high conductivity, some high performance vehicles require them.


Platinum Spark Plugs

The hard platinum metal in the electrode of a platinum spark plug allows it to last longer than a copper plug, retaining its edge better. Due to temperature resistance, platinum spark plugs tend to run hotter, preventing fouling and buildup of deposits. These are usually best for newer vehicles with electronic distributor-based ignition systems.


Double Platinum Spark Plugs

Feature two discs to accommodate a backwards-jumping side-to-center spark. Because sparks are allowed to fly in both directions, double platinum spark plug electrodes don't wear as fast. You don't want to install single platinum plugs if your owner's manual recommends a double platinum spark plug.


Iridium Spark Plugs

Harder than platinum, and, in most cases, lasts about 25 percent longer than platinum spark plugs of similar design. Iridium plugs usually feature the smallest diameter center, which can increase efficiency by reducing voltage needed to create a spark. Iridium is also famous for continuing to fire under extreme conditions. If your manual specifies iridium spark plugs, best practice is to absorb the extra cost associated with this rarer metal for best performance.


Double Iridium Spark Plugs

Like double platinum spark plugs, double Iridium spark plugs feature two discs of rare metal for increased performance and durability. Double Iridium Spark Plugs are designed to deliver the firepower necessary under any driving conditions, especially extreme heat or continual high-speeds, and can provide up to 4 times the normal life of service compared to a standard copper spark plug.

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Be sure to consult your owner’s manual, a repair guide, an AutoZoner at a store near you, or a licensed, professional mechanic for vehicle-specific repair information. Refer to the service manual for specific diagnostic, repair and tool information for your particular vehicle. Always chock your wheels prior to lifting a vehicle. Always disconnect the negative battery cable before servicing an electrical application on the vehicle to protect its electrical circuits in the event that a wire is accidentally pierced or grounded. Use caution when working with automotive batteries. Sulfuric acid is caustic and can burn clothing and skin or cause blindness. Always wear gloves and safety glasses and other personal protection equipment, and work in a well-ventilated area. Should electrolyte get on your body or clothing, neutralize it immediately with a solution of baking soda and water. Do not wear ties or loose clothing when working on your vehicle.

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