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Different Types Of Spark Plugs: Understanding The Differences

A car's spark plug. There are a lot of different spark plugs to choose from. How do you know which one your car uses? Here's a helpful guide to get the right spark plugs for your car.

There are different types of spark plugs available, and they’re typically defined by the metal used to construct them. These plugs all have one thing in common: They help generate the energy your vehicle’s internal combustion engine needs to get the car from point A to point B.

Below, we’ll take a look at the various types of spark plugs currently on the market. We’ll examine each plug’s unique characteristics, as well as its strengths and weaknesses.

Copper Spark Plugs

Copper spark plugs are one of the most common choices on the market. Despite their name, only the inner core of these plugs is made of copper. Their electrodes are covered by a nickel-alloy coating.Spark Plug

This type of spark plug is best suited for vehicles built prior to the 1980s that have low-voltage distributor based ignition systems. Also, copper spark plugs tend to run cooler, and this allows them to deliver unusually strong performance when used with engines that have turbochargers or high compression ratios. For this reason, they’re often used as original equipment by manufacturers of late-model high-performance vehicles. Finally, copper spark plugs are your best bet if your engine uses natural gas.

Copper spark plugs tend to cost less than other choices available. Their big drawback concerns longevity. They tend to have shorter life spans than other types of plugs on the market and typically need to be changed every 20,000 miles.

Platinum Spark Plugs

Platinum spark plugs feature platinum discs welded to the tips of their electrodes. Platinum’s most notable quality is its resilience — it’s harder than nickel alloy and it doesn’t erode as quickly. As a result, these plugs have a longer life span than ones with nickel-alloy electrodes. Some platinum spark plugs can provide up to 100,000 miles of service.

If you have a newer vehicle with an electronic distributor-based ignition system, platinum spark plugs are an ideal choice. Also, if your car’s owner’s manual specifically advises you to use platinum spark plugs, stick to this recommendation, and don’t downgrade.

Iridium Spark Plugs

These spark plugs feature iridium discs welded to their electrodes. Platinum is harder than nickel-alloy, but iridium is harder than platinum. How much harder? Iridium is six times harder and eight times stronger than platinum, and it has a melting point that’s up to 700 degrees higher. These qualities enable iridium spark plugs to last up to 25% longer than plugs with platinum tips.

If your owner’s manual recommends iridium spark plugs, follow this advice. Downgrading could result in diminished engine performance.

Iridium-tipped plugs are superb at conducting electrical energy, and they offer top-rate firing efficiency. Keep in mind, though, that since iridium is a costly precious metal, these plugs are usually the most expensive choices on the market.

Silver Spark Plugs

Silver spark plugs feature electrodes tipped with silver. They rate highly when it comes to thermal conductivity, but they don’t last as long as plugs tipped with platinum or iridium. You’ll usually find them in motorcycles or older European performance cars.

Each type of spark plug brings something unique to the table. Take a thorough look at what each of these plugs has to offer when making a purchasing decision, and consult your car’s owner’s manual.

Check out all the electrical & ignition system products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on the different types of spark plugs, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.


Warren Clarke View All

I'm a writer and editor who's a regular contributor with the New York Daily News and Carfax, and my content has appeared in over 20 publications. I've written content that covers industries such as automotive, medical, insurance, healthcare, real estate, plumbing, pest control, dental and hospitality.

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