The 10 Best Spark Plugs
Updated by · How we research
Iridium, platinum and copper plugs from six brands, compared by fit and service life. For most newer cars, the NGK IFR5L-11 Laser Iridium is the pick. When users buy our independently chosen editorial selections, we may earn commissions to help fund the Wiki.
The right plug is the exact part number your engine's maker lists, and the brand matters far less than that match. A long-life iridium plug can run about 100,000 miles, while basic copper may need changing after a quarter of that. This list is for drivers doing their own tune-up or checking the parts on a shop's quote.
Editor's Notes
October 22, 2026, by Ezvid Wiki Admin:
The NGK IFR5L-11 Laser Iridium now leads, because most newer engines need a long-life plug and NGK's own figures give its Laser line about twice the service life of its Iridium IX line. The NGK BKR5EIX-11 Iridium IX stays, now as the upgrade for older engines that came with copper.
New picks follow the factory suppliers: the Denso SK20HR11 Iridium Long Life for Toyota and Lexus, the ACDelco 41-162 for GM and the Motorcraft SP432 for Ford, plus the NGK BKR5E-11 copper plug, the NGK G-Power TR5GP and the Autolite Platinum AP5263. The Denso PK20TT and Bosch 6701 Platinum stay.
The Bosch Fusion and SplitFire SF512E are gone from sale, the Autolite APP104 had no current offer, and the Champion J19LM turned out to be a lawn-mower plug. We dropped the E3 E3.62 over thin stock and unproven fuel claims, and the Brisk Premium Evo as a niche racing plug. The ranking rests on NGK's comparison of its two iridium lines, GM's and Ford's parts data, and a dyno session that found no power gain from pricier plugs.
March 15, 2021:
All of our recommendations here are still valid, partly because the actual brand of spark plug doesn't always make a huge amount of difference. Just as important are the type of engine you're working with and even its specific spark plug fitment, which can vary greatly among cars and trucks.
With that in mind, Bosch Platinum and NGK Iridium remain two of the most popular for good reason. They both offer premium build quality and perform consistently over a long period of time - longer, in fact, than some used vehicles themselves will probably last. Some options, like the Brisk Premium Evo, are meant to withstand high-octane fuel at high combustion ratios, something that only heavily tuned vehicles need to worry about. Others, such as the Champion J19LM, are engineered specifically for smaller equipment such as lawnmowers.
October 09, 2019:
Removed the Autolite 3923 because of quality-control issues. Added the E3 E3.62 because they have a very innovative design. The electrode configuration gives the arc multiple places to migrate to, which will extend the plug's life. It avoids arc-shielding concerns (which can result in inefficient combustion) because it is more open than other similarly designed plugs.
When considering what plugs to buy for your car, always follow manufacturer recommendations for electrode material. Platinum, iridium, and copper all have different heat and conductive properties whose relevance to an engine will vary. Some engines require colder plugs while others require hotter ones. As for plugs whose side electrode extends further than stock plugs, this should be avoided unless you first verify that the piston's top-dead-center is low enough to avoid contact with the plug. This should be measured from the nut and not from the base of the center electrode.
Auto repair can be dangerous and should only be performed by trained technicians to avoid personal injury or damage to equipment.
Special Honors
NGK Spark Plug Part Finder NGK's site looks up the right plug by year, make, model and engine, and it lists NGK's cross-references to other brands' part numbers. It's a quick way to confirm a part number before buying any brand, though your owner's manual has the final word. ngksparkplugs.com
Start With The Part Number, Not The Brand
A colder plug only makes sense on a tuned or boosted engine, and only when the tuner says so.
A plug has to match its engine in several ways at once: thread size, reach (how far the threads go into the head), seat type, heat range and gap. The thread is usually 10, 12, 14 or 18 millimeters, and a plug with too long a reach can hit a valve or piston, while one too short leaves carbon to build up in the exposed threads (Wikipedia). Never swap a tapered-seat plug for a gasket-seat one.
Heat range is the trap that catches brand-switchers. It describes how fast the tip sheds heat, and the numbers run in opposite directions: on NGK and Denso plugs a higher number means a colder plug, while on Champion, Bosch and ACDelco a higher number means a hotter one. A colder plug only makes sense on a tuned or boosted engine, and only when the tuner says so.
So the safest buying method is the plain one. Look up the part number in your owner's manual or in the plug maker's online finder, then buy that number or the maker's direct cross-reference. If you check the gap on a fine-wire plug, use a wire-type gauge so you don't press on the delicate tip.
Copper, Platinum Or Iridium
Copper-core plugs with nickel tips are the cheapest and conduct well, but they wear fastest and usually need changing every 20,000 to 30,000 miles. Iridium is about six times harder than platinum and can last up to about 100,000 miles, at several times the price per plug (Jalopnik). Platinum sits in between.
Where the precious metal goes matters as much as which metal. NGK splits its iridium plugs into two lines: the Laser series puts iridium on the center tip and platinum on the ground electrode and is designed for 80,000 to 100,000 miles, while the Iridium IX has precious metal on the center tip only and is designed for 40,000 to 50,000 miles (NGK). The two perform about the same; the difference is how long they last.
The rule that follows is simple. If your engine left the factory with a long-life dual-tip plug, replace it with the same kind, or you'll be pulling plugs again in half the time. If it came with copper, a copper plug is fine, and cheap plugs work well in ordinary engines (SlashGear). Fine iridium and platinum tips shouldn't be bent to change the gap, because the welded tip can break off.
How The Big Spark Plug Brands Compare
NGK and Denso are the two giant Japanese makers. NGK fits factory plugs for many Japanese carmakers and others, and Denso, part of the Toyota group, says it was first to put platinum and iridium in plugs (Denso). ACDelco and Motorcraft are the house brands of GM and Ford, so they're the natural choice for those engines (Ford). Bosch is the big German supplier, Autolite and Champion are long-running American names, and Champion's copper plugs are still the default in many lawn mowers.
Independent rankings mostly agree on the top tier. SlashGear's brand ranking puts NGK first and Bosch, Champion and Denso close behind, and it warns against no-name marketplace brands with fouling complaints and error-filled descriptions (SlashGear). We found no independent test of budget brands such as A-Premium, so buy them only if you're comfortable with an unknown.
Don't expect a pricier plug to add power. In a dyno session on a 5.3-liter V8, copper, platinum and multi-ground plugs made about the same power (BangShift). Makers like E3 claim fuel savings for their designs, but those claims are strongest for small engines (E3). The right part number in good condition is what makes the difference.
How we researched this
We compared 20 current spark plugs from 10 brands and screened 13 in depth. We read makers' documents where they were published, including NGK's guide to its two iridium lines and Ford's Motorcraft parts page, along with parts-catalog cross-references, independent roundups and a published dyno session, and we analyzed patterns in owner feedback. We checked each brand for recalls with the U.S. Consumer Product Safety Commission. The 3D models are built from published dimensions.
Sources (10)
- NGK: Iridium IX vs. OE iridium spark plugs
- Ford: Motorcraft SP432X spark plug
- Denso auto parts
- E3 Spark Plugs
- Wikipedia: Spark plug
- Jalopnik: copper vs iridium spark plugs
- SlashGear: spark plug brands ranked
- SlashGear: cheap vs expensive spark plugs
- BangShift: spark plug dyno test
- U.S. Consumer Product Safety Commission recalls
Frequently asked questions
What is the best spark plug brand?
For most cars, the brand that made the original plug: NGK or Denso for most Japanese cars, ACDelco for GM and Motorcraft for Ford. Bosch, Autolite and Champion are solid too. The right part number matters more than the logo.
Are iridium spark plugs better than platinum or copper?
Iridium lasts longest, often up to about 100,000 miles in long-life designs, while copper usually needs changing every 20,000 to 30,000 miles. Use the type your vehicle maker specifies; a downgrade means more frequent changes.
Do better spark plugs add horsepower or mileage?
Not in a way you'd notice on a healthy engine. Dyno sessions have shown no clear power gain from premium plugs. Fresh plugs of the right type restore lost performance, but they don't add new performance.
When should I replace my spark plugs?
Follow the interval in your owner's manual. Signs of worn plugs include a rough idle, misfires, hard starting and falling fuel economy.
Are cheap brands like A-Premium any good?
We found no independent test of them. Some owners use them without trouble, but counterfeit and off-brand plugs are a known problem, so for a long-life engine a name-brand plug from the maker's own storefront is the safer buy.
Which spark plugs are best for a Toyota?
Denso, Toyota's group supplier, or NGK. Most newer Toyota engines use long-life iridium plugs, so match the Denso or NGK part number that crosses to your engine's factory plug.
