How to Choose the Best Spark Plugs

Brian Jones

March 20, 2025

5 min read

Brian Jones

March 20, 2025

5 min read

A set of four spark plugs lined up neatly, in front of a set of worn spark plugs, resting on the edge of a car’s engine compartment. — Choosing the best spark plug comes down to brand, material, and matching your vehicle’s specifications.

The key to choosing replacement spark plugs comes down to three primary factors.

Brand/quality: Choose reliable brands with a warranty. Even the best spark plugs are affordable.

Vehicle specifications: Spark plugs aren’t universal, and only spark plugs designed for your vehicle will fit. Check your owner’s manual to determine the recommended type and gap size.

Material: Spark plugs come in three main types: copper, platinum, and iridium. Copper plugs are the most affordable, but they only last around 20,000 miles, so you need to replace them more often. We believe that the best-performance spark plug is usually copper. While these don’t last as long, they are considered the top-rated performance spark plugs because they run cooler and provide more power. Typically, copper plugs are installed from the factory in turbocharged engines for these reasons.

Platinum and iridium are built stronger, so there’s a higher price upfront. Yet, they could last 100,000 miles or longer, so they may end up saving money in the long run.

Go with iridium if you want the best spark plugs for fuel economy. Because they use fine wire design, there’s a more efficient spark, providing better combustion. With an optimized engine performance, iridium are the best spark plugs for fuel efficiency but they cost more than other types. It’s unclear if the savings at the pump are worth it.

A set of four iridium spark plugs, displayed on a white background. — Iridium electrodes are noticeably thinner than copper electrodes.

Best copper spark plug: NGK makes great spark plugs, and one of the best copper spark plugs is its V-Power series. These have a unique design to enhance engine performance and ignition efficiency. Spark plugs from original equipment manufacturers (OEM) also offer great quality. For instance, ACDelco is an example of an OEM brand for GM.
Best platinum spark plug: OEM brands make great platinum spark plugs. Denso is to Toyota as ACDelco is to GM, and we like the Denso Platinum TT plug. Additionally, NGK makes a good plug in the NGK Iridium IX, which combines the benefits of both platinum and iridium.
Best iridium spark plug: We recommend Denso Iridium Power spark plugs and the Bosch Double Iridium plugs. The first improves throttle response, while the latter has a laser-welded tapered ground electrode for better ignition performance.

Which Companies Make the Best Spark Plugs

A set of four Bosch platinum spark plugs, displayed on a white surface. — The electrode width of platinum spark plug electrodes are similar to iridium plugs.

It’s difficult to choose the best spark plug brand because there are so many to consider. The list of companies with high reviews include Bosch - opens in new window or tab., Champiion - opens in new window or tab., Denso - opens in new window or tab., and NGK - opens in new window or tab., all ensuring better engine performance.

You may prefer to stick with manufacturer-specific brands, such as ACDelco - opens in new window or tab. (GM), Motorcraft - opens in new window or tab. (Ford), and Mopar - opens in new window or tab. (Chrysler, Jeep, Dodge). Look for favorable customer reviews, and make sure they come with a decent warranty.

Other Factors

A set of six of copper-core NGK spark plugs, displayed on a white surface. — The electrodes on this set of NGK R spark plugs use copper cores with nickel-tips.

Buy a spark plug gap tool: When you receive the new spark plugs, it’s important to check the gap. Many plugs come gapped from the factory, but some require the use of a spark plug gap tool - opens in new window or tab.. Any reliable tool company can provide a dependable option, such as Craftsman, MAC Tools, or Snap-On. Learning how to gap a spark plug - opens in new window or tab. is easy. It only takes a few minutes to double-check the gap before installing the new plugs.

Shop for spark plug wires at the same time: If you learn how to replace spark plugs - opens in new window or tab. on an older vehicle, you will inevitably encounter spark plug wires as well. Spark plug wires - opens in new window or tab. are one of the easiest DIY upgrades to the ignition system - opens in new window or tab., with several quality brands to select from, including Accel, Denso, MSD, and NGK.

Not for diesel engines: No, there’s no such thing as a diesel spark plug. Instead of a spark plug, diesel engines contain glow plugs - opens in new window or tab.. Diesel engines use compression ignition rather than spark, so there’s no need for spark plugs.

About the author

Brian Jones

Brian worked for several decades as an ASE Certified Master Technician in dealerships before starting his used car lot. Today, he writes for top automotive publications including Motor1. In his spare time, he's dreaming of an escape to the country's best trails in an off-road beast.

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This article is meant to provide general guidance only. Automotive maintenance, repair, upgrade, and installation may depend on vehicle-specifics such as make and model. Always consult your owner's manual, repair guide for specific information for your particular vehicle and consider a licensed auto-care professional's help as well, particularly for advance repairs.