If you are replacing spark plugs, the brand matters—but the exact part number matters more. A correctly specified Champion or Autolite plug is a better choice for a particular engine than a premium NGK or Denso plug with the wrong reach, heat range, electrode design, or gap.
The ranking below weighs OE integration, application coverage, current product range, documented technical designs, and ease of finding the correct replacement. It is not a universal laboratory test of every plug each brand sells. Use the vehicle manufacturer’s catalog or the plug maker’s part finder before ordering.
| # | Preview | Product | Price | |
|---|---|---|---|---|
| 1 |
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NGK # 3186 G-Power Platinum Spark Plugs TR5GP - 8 PCSNEW | $34.76 | Buy on Amazon |
| 2 |
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NGK Spark Plug SILZKR7B11 9723 Pack of 6 | $67.26 | Buy on Amazon |
| 3 |
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NGK 6619 Iridium Spark Plugs LFR6AIX-11-6 Pack | $45.95 | Buy on Amazon |
| 4 |
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NGK Set of 16 Iridium IX Spark Plugs For Chrysler Dodge Jeep Ram 5.7 6.4 V8 | $158.99 | Buy on Amazon |
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Major spark plug brands ranked from worst to best
| Rank | Brand | Best use |
|---|---|---|
| 1 | NGK | Best all-around aftermarket coverage and import applications |
| 2 | Denso | Japanese vehicles, OE replacement, and performance-oriented designs |
| 3 | Motorcraft | Ford and Lincoln applications |
| 4 | Bosch | Bosch-specified and many European applications |
| 5 | Champion | OE-specific domestic, marine, powersports, and specialty engines |
| 6 | Autolite | Value-focused replacements and older domestic applications |
“Worst” in this list does not mean a brand makes unusable spark plugs. It means the brand is less compelling as a universal recommendation than the brands above it. Application-specific fit can reverse the order completely.
1. NGK: best overall
NGK is the safest general recommendation because it combines broad coverage with a deep range of original-equipment-style and aftermarket plugs. The company says its ignition products cover 95% of import and domestic vehicles in the United States, and its range includes Nickel, Iridium IX, Laser Iridium, and Ruthenium HX designs. See the NGK product overview and its current iridium range.
#1 Best Overall
- G-Power Platinum
- Designed to operate over a much wider heat range than ordinary plugs
- Resists carbon buildup and pre-ignition
- Patented triple gasket sealing process eliminates the possibility of combustion gas leakage
NGK’s biggest advantage is not simply the word “iridium” on the box. Its Laser Iridium plugs are developed around manufacturer-specific requirements and are generally intended for approximately 80,000 to 100,000 miles. Iridium IX plugs are more performance-oriented and are typically rated around 40,000 to 50,000 miles. That difference is important: an Iridium IX plug is not automatically an upgrade over the Laser plug specified for your engine.
Choose NGK when it is the OE or catalog-specified brand, particularly for many Asian and import applications. Match the exact heat range, thread dimensions, reach, resistor specification, seat type, electrode configuration, and gap. NGK warns that incorrect reach or projection can cause overheating or contact with the piston or valves.
Best NGK choice: the exact OE-style Laser or other cataloged plug for the vehicle—not necessarily the most expensive iridium option.
2. Denso: best alternative and performance-oriented choice
Denso is close enough to NGK that the two brands are effectively tied for many Japanese and Asian applications. Denso’s U.S. catalog includes OE-Type, Double Platinum, Iridium Long Life, U-Groove, Iridium TT, Platinum TT, Iridium Power, and Iridium Racing lines. Its range gives buyers more than one way to match an OE replacement, a long-life plug, or a specialized performance application.
The Iridium TT is one of Denso’s notable designs. It uses a 0.4-mm iridium center electrode and a 0.7-mm platinum ground tip. Denso says the configuration reduces required firing voltage, resists electrode wear, and is designed for more than 100,000 miles. Those are manufacturer claims, not proof that every engine will gain power or fuel economy from the plug.
Denso also has substantial OE involvement and says its parts are supplied for hundreds of vehicle models and engineered to meet or exceed OE standards. The practical rule is straightforward: if the parts catalog specifies Denso, use Denso; if it specifies NGK, use NGK. Do not substitute an Iridium TT or Iridium Power plug merely because it sounds more advanced.
Best Denso choice: the Denso OE-type or long-life part number listed for the engine. Iridium Power and Iridium Racing are specialty products, not automatic upgrades for a stock daily driver.
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Motorcraft ranks third overall because its strongest argument is precise Ford application matching. Ford says Motorcraft spark plugs are matched to specific engines, tested to Ford specifications, and designed to support performance, emissions compliance, and durability. For a Ford or Lincoln, that OE relationship is more valuable than a generic brand ranking.
Rank #2
- TRUSTED OEM BRAND: NGK is a global leader in ignition components, supplying spark plugs for a wide range of domestic and import vehicles.
- CONSISTENT IGNITION PERFORMANCE: Designed to support reliable starts, smooth engine operation, and consistent combustion under normal driving conditions.
- ADVANCED ELECTRODE DESIGN: Engineered with application-specific electrode technology (copper, iridium, or platinum) to support efficient spark and durability.
- CORROSION-RESISTANT PLATING: Trivalent metal plating helps provide corrosion resistance and supports easier removal over time.
- DIRECT REPLACEMENT FIT: Manufactured to meet OE specifications for fit, form, and function—verify compatibility with your vehicle before purchase.
The current Motorcraft range includes platinum-iridium, fine-wire double-platinum, platinum, nickel, and standard copper-core designs. Ford lists typical service intervals from up to 60,000 miles for some standard designs to 100,000 miles for several precious-metal plugs. The correct interval still depends on the engine, plug, operating conditions, and the maintenance schedule for the vehicle.
Motorcraft is often the right answer for Ford engines that are sensitive to electrode configuration or plug design. The same type of plug installed at the factory is generally available through Ford’s parts system for applicable applications. That does not make Motorcraft universally superior to NGK or Denso; it makes it particularly strong when the vehicle catalog calls for it.
Best Motorcraft choice: the Motorcraft part number listed by Ford for the specific engine and model year.
4. Bosch: strong OE-style range, but application-dependent
Bosch offers a broad lineup that includes EVO, Double Iridium, Double Iridium Pin-to-Pin, Iridium, Double Platinum, Platinum, Nickel with Copper, and Platinum+4 plugs. The company’s EVO line is aimed at modern turbocharged gasoline direct-injection engines and is designed to withstand abnormal combustion events, including what Bosch describes as “mega knocking.”
Bosch’s Double Iridium Pin-to-Pin plugs are marketed as OE-equivalent in fit, form, and function and carry a seven-year satisfaction guarantee on the current U.S. product page. Bosch also lists a four-year warranty for its platinum plugs and claims service life of up to twice that of standard copper plugs.
Bosch is a sensible choice when the vehicle catalog specifies Bosch, especially on European applications or where a Bosch OE-style design is required. Its lower position is not a verdict against Bosch quality. It reflects the fact that a Bosch plug with a different electrode arrangement or heat range is not a valid replacement just because it is also an iridium plug.
Best Bosch choice: the OE-equivalent or EVO part selected through Bosch’s application catalog, not a universal “best” Bosch plug.
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5. Champion: best as an OE- or application-specific choice
Champion’s current automotive range includes OE, iridium, platinum, and Copper Plus products. Its OE plugs use iridium or platinum electrodes for improved ignitability and longer service life. Champion also directs buyers to its Part Finder, which is the right approach because spark-plug selection cannot be reduced to choosing the most expensive electrode material.
Rank #3
- Iridium Spark Plugs
- Designed to operate over a much wider heat range than ordinary plugs
- Resists carbon buildup and pre-ignition
- Patented triple gasket sealing process eliminates the possibility of combustion gas leakage
Champion remains especially relevant for certain domestic vehicles, powersports engines, marine applications, lawn equipment, and racing products. That wider coverage makes it a strong specialist brand even though it is less useful as a one-size-fits-most recommendation for passenger cars.
A budget Champion plug should not be used to judge the entire brand. Compare the exact Champion part number with the plug specified for the engine. If Champion is the OE specification, it can be a better choice than a higher-priced aftermarket alternative that differs in reach, heat range, or ground-electrode design.
Best Champion choice: the OE or application-specific part identified by Champion’s Part Finder.
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6. Autolite: good value, but not the strongest universal premium pick
Autolite is last in this editorial ranking, but it is not limited to old-fashioned low-cost copper plugs. Its current catalog includes Iridium Ultra, Iridium XP, Double Platinum, High Thread Pro, Platinum, Copper, and Glow Plugs. Autolite describes Iridium Ultra as its premium OE-replacement line and Iridium XP as a premium fine-wire option.
Autolite can make sense for older domestic engines, cost-conscious repairs, and applications where the catalog specifically lists Autolite. Its premium products also give buyers an alternative to the better-known Japanese brands without automatically dropping to a basic nickel-alloy plug.
One reason to verify the current part number is Autolite’s design-uniformization notice. Certain Iridium XP and Double Platinum SKUs changed to a traditional ground-wire and center-electrode design, so older product photographs and forum descriptions may not accurately show the current plug. Check the current catalog rather than buying based on an old image.
Best Autolite choice: Iridium Ultra, Iridium XP, or Double Platinum when that exact line and part number match the application.
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Correct dimensions and heat range
A replacement plug must have the correct thread diameter, thread reach, seat type, terminal, resistor specification, heat range, projection, electrode configuration, and gap. A plug that physically threads into the cylinder head may still be wrong. Excessive reach or projection can contact internal engine components, while an unsuitable heat range can contribute to fouling or overheating.
Rank #4
- This 16 pack NGK Iridium IX Spark Plug is compatible with Ram 1500 2024, 2023, 2022, 2021, 2020, 2019, 2018, 2017, 2016, 2015, 2014, 2013, 2012, 2011 5.7L V8
- Genuine NGK Parts
- Includes original packaging and hardware
- Direct replacement auto parts
- Confirm vehicle fitment with Amazon Confirmed Fit
Electrode material and construction
Iridium and platinum primarily improve erosion resistance, spark stability, ignitability, and service life. They do not automatically add horsepower to an otherwise stock engine. A fine-wire plug may require less firing voltage, but the result depends on the ignition system, engine calibration, combustion chamber, and correct application.
“Copper plug” is also imprecise terminology. Standard plugs generally use a nickel-alloy firing electrode with a copper core to move heat away from the firing end. Copper is normally not the exposed electrode material.
Waste-spark ignition requirements
Waste-spark systems fire paired plugs with opposite electrical polarity. That difference changes which electrode wears faster. Many such systems require double-precious-metal plugs because a single precious-metal or nickel plug may erode prematurely. Follow the application catalog instead of assuming that any iridium plug is suitable.
Installation mistakes that shorten plug life or damage the engine
- Do not automatically use anti-seize. NGK says its trivalent-plated plugs are intended to be installed dry. Anti-seize can alter tightening torque by as much as 20%, increasing the possibility of shell stretch, thread breakage, and poor heat transfer. Use the plug manufacturer’s instructions.
- Do not blindly re-gap a fine-wire plug. If the specified gap must be adjusted, move only the ground electrode. Do not pry against the fine-wire center electrode or the ceramic insulator.
- Use the specified torque. Under-torquing can reduce heat transfer and contribute to overheating. Over-torquing can stretch the shell, damage the gasket or taper seat, crack the insulator, or damage cylinder-head threads. Clean the threads and use a torque wrench where access allows.
- Keep dirt out of the plug well. Blow debris away before removing the old plug. On coil-on-plug engines, dirt or moisture in the well can cause misfires that may be incorrectly blamed on the new plug.
- Buy through a reliable source. Counterfeit plugs can have incorrect markings, plating, electrode dimensions, or internal construction. Buy from the manufacturer, a listed authorized retailer, or a reputable parts distributor. NGK’s current authorized-seller list includes major chains such as AutoZone, Advance Auto Parts, O’Reilly, NAPA, and Summit Racing.
How to choose the right plug in practice
- Find the vehicle’s engine code, model year, and application. A model may use different plugs depending on engine, emissions package, or production date.
- Check the owner’s manual, factory service information, or a manufacturer catalog.
- Compare the complete part specification—not just thread size or electrode material.
- Prefer the OE brand and design when the manufacturer identifies one.
- Confirm the supplied gap and change it only if the application instructions require adjustment.
- Install the plug with the specified torque and without unapproved lubricants or anti-seize.
Bottom line
NGK is the best general recommendation, with Denso very close behind. Motorcraft is the smarter choice for Ford and Lincoln, Bosch is strong where its OE-style design is specified, Champion is particularly useful for OE and specialty applications, and Autolite offers credible value options beyond its basic plugs.
The ranking should be used as a starting point, not a substitute for fitment information. The correct plug number, heat range, reach, electrode design, gap, and installation torque matter more than winning a brand popularity contest.
FAQ
Is NGK better than Denso?
Neither is universally better. NGK is the strongest all-around recommendation because of its broad coverage and OE-specific range, while Denso is an excellent alternative and is often the right choice when the vehicle catalog specifies it.
Do iridium spark plugs increase horsepower?
Not automatically. Iridium mainly improves electrode durability, ignitability, and spark stability. A correctly specified iridium plug may support consistent operation, but it does not by itself create a meaningful power increase in a stock engine.
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Can I use a different spark plug brand if the size matches?
Not necessarily. The replacement must also match heat range, reach, seat type, resistor design, projection, electrode configuration, and gap. Use the manufacturer’s cross-reference or application catalog rather than relying on thread size alone.
Should I put anti-seize on new spark plugs?
Do not apply it automatically. NGK says its trivalent-plated plugs are installed dry and warns that anti-seize can change tightening torque by as much as 20%. Follow the instructions for the specific plug and engine.
The Bottom Line
Best overall: NGK. Best alternative: Denso. Best for Ford and Lincoln: Motorcraft. Bosch, Champion, and Autolite can all be excellent when their exact cataloged plug matches the engine. The correct application beats the brand ranking every time.
Quick Recap
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
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