Reviews

LAST UPDATED:  October 16, 2019

The Best Spark Plugs (Review & Buying Guide) in 2020

Keep your vehicle’s engine going strong with these top spark plugs

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PUBLISHED ON October 16, 2019

Don’t let their small size fool you—spark plugs emit an electrical spark across a tiny gap to ignite the combustion required to start your vehicle. By setting your motor’s pistons in motion, your ride can roar to life, stay running, and deliver a smooth burn of the compressed air-fuel mixture. Is your engine due for a spark plug replacement? Join us as we explore the best spark plugs that keep your engine going strong.

Best Overall
NGK (6619) LFR6AIX-11 Iridium IX Spark Plug
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Summary
Summary

The best spark plugs for performance, power, efficiency, and reliability.

Pros
Pros

A good design that is unlikely to misfire or malfunction, superb performance/efficiency, and long lifespan.

Cons
Cons

On the pricey side for a spark plug replacement.

Best Overall
NGK (6619) LFR6AIX-11 Iridium IX Spark Plug
Best Value
Denso (4504) PK20TT Platinum TT Spark Plug
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Summary
Summary

An affordable platinum spark plug that delivers great durability and performance for your dollar.

Pros
Pros

Excellent price, durable, double platinum tip for enhanced performance.

Cons
Cons

The gap is occasionally set incorrectly, performance isn’t on par with iridium spark plugs.

Best Value
Denso (4504) PK20TT Platinum TT Spark Plug
Honorable Mention
Bosch ZGR6STE2 Copper with Nickel Spark Plug
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Summary
Summary

These plugs boost cold starts, enhance fuel ignition, and foster optimum performance, reliability, and heat transfer.

Pros
Pros

They have a long lifespan and may increase gas mileage and boost performance in certain vehicles.

Cons
Cons

The factory set gap may not be correct, and they may not fit all vehicles listed in the specs.

Honorable Mention
Bosch ZGR6STE2 Copper with Nickel Spark Plug

Don’t let their small size fool you—spark plugs emit an electrical spark across a tiny gap to ignite the combustion required to start your vehicle. By setting your motor’s pistons in motion, your ride can roar to life, stay running, and deliver a smooth burn of the compressed air-fuel mixture. Is your engine due for a spark plug replacement? Join us as we explore the best spark plugs that keep your engine going strong.

Best Spark Plug Reviews & Recommendations 2020

Best Overall

The NGK 6619 Iridium IX Spark Plugs snags the top pick in our spark plug comparison because they offer the best mix of high-performance, fuel efficiency, durability, and dependability. Featuring an iridium construction, these high-quality spark plugs provide a longer lifespan than copper and platinum spark plugs.


Their ultra-fine electrode wire promises superior fuel efficiency as well as silky-smooth engine idle and response. You can also expect a healthy boost in power and torque thanks to the optimal air-fuel mixture that these iridium spark plugs generate. They receive top marks for durability with such impressive features as metal plating to resist corrosion and seizing, as well as a long insulator nose to prevent fouling. 


We were hard pressed to come up with any cons for these spark plugs, but if we had to ding them for something, it would be their rather expensive price per spark plug. This higher price may seem like a big ask for more frugal motorists, but the exquisite quality and peerless performance that the NGK 6619 spark plugs deliver make them well worth their cost.

Best Value

If you’re in the market for solid all-around spark plugs that are easy on your wallet, look no further than the Denso 4504 PK20TT Platinum Spark Plugs. These value-priced platinum plugs pack a whole lot of performance, efficiency, and durability for a downright reasonable price.


Featuring a dual-platinum construction with a platinum disc and platinum electrode tip, these spark plugs provide a reliable spark to generate smooth, reliable combustion of the air-fuel mixture. This translates to great engine dependability, fuel efficiency, and performance. Another impressive feature is purified alumina powder, which is used as an insulator to increase thermal conductivity for maximum longevity. 


However, there are a few faults that we found with these double-platinum spark plugs. Occasionally, the gap is incorrectly set on some of the plugs. This is why it’s critical that you inspect the gap and adjust it accordingly. In addition, these double-platinum plugs cannot match the quality, performance, and longevity that iridium spark plugs boast. Nonetheless, we believe that Denso 4504 PK20TT Platinum Spark Plugs are some of the best affordable spark plugs for your car, truck, or SUV. 

Most Reliable

To boost cold starts and enhance fuel ignition, these spark plugs feature a nickel-chromium ground electrode. They have heavy-duty yttrium enhanced copper core center for optimum performance, reliability, and heat transfer.


These plugs are very durable and have a long lifespan. The nickel-plated shell provides anti-seize and corrosion protection. No gapping is required, and the plug's ribbed insulator prevents flashover. The plugs remedy misfires in certain vehicles, can increase mileage in some vehicles, and may boost performance by a noticeable amount.


One issue with these plugs is they may not fit certain vehicles even though the specs indicate that they will. They may also be shipped in non-padded boxes with the plugs rolling around loosely in the package, which could damage them. Another problem is while the gap is set at the factory, they still may need to be slightly adjusted.

Most Durable

This OE replacement plug has a long lifespan and is very durable. The iridium firing pin is welded with a 360-degree continuous laser, and the copper core is designed to reduce fouling. 


The wire is ultra-fine, and the nickel-plated shell prevents it from seizing. No gapping is required, and the plug has corrosion protection. One of the best things about these plugs is they last a long time, which is important if you have an engine in which the plugs are difficult to access. While you may not notice a change in mileage after you install them, you may see a boost in performance. They are also very reliable, and you don't need a special gap tool for installation.


However, they are not compatible with all vehicles, so you need to double-check the gap to see if they will fit your make and model. Also, there have been some complaints that the boxes get damaged during shipping, and the plugs roll around loosely, which can potentially damage them.

Honorable Mention

The NGK 4929 spark plug for motorcycles and UTVs has a solid copper core for more spark and a long insulator nose to minimize fouling. It's dipped in zinc to prevent corrosion and features insulators with corrugated ribs to reduce flashover. To eliminate gas leakage, the plug has a triple gasket seal.


These plugs work well on a variety of bikes, including Suzukis, Triumphs, and Honda Recon 250s, among others. They work as expected and keep your bike running well in temperatures as low as 24-degrees Fahrenheit or as high as 100-degrees Fahrenheit. Overall, they have clean, crisp threads and are easy to install.


However, they won't fit on all bike models. Also, while they're a decent price, you may be able to find a cheaper alternative. In addition, the plugs don’t come with screw-on caps, which you may need for certain applications.

Honorable Mention

NGK's Iridium IX spark plug is designed to boost throttle response and prevent fouling. Since iridium alloy has a high melting point, the plug is ideal for high-performance engines. It features a 0.6mm laser-welded fine iridium tip for a longer lifespan and a stable spark. It's designed to reduce and prevent flashover, combustion gas leakage, and electrical quenching. 


The plugs have anti-corrosion and anti-seizing characteristics. It's common for a vehicle to exhibit an improvement in acceleration and a slight increase in gas mileage after installing these plugs. They are simple to install, and your vehicle will run smoother and more efficiently. Overall, they're great for turbocharged and supercharged cars.


The biggest problem with these plugs is that you may need to regap them for proper installation. Some consumers have also complained that they've noticed no change in performance after installing them.

Honorable Mention

This plug is ideal for performance-driven vehicles as well as older vehicles that need conventional plugs. ACDelco boasts that these plugs can last up to 100,000 miles, depending on the application. The iridium tip minimizes spark erosion, and it's designed to prevent compression leakage. The plug also increases fuel efficiency because the spark gap stays nearly the same during its lifespan.


The plugs come perfectly gapped for certain makes and models, such as Chevy and GM vehicles. You will notice a difference in startup and performance after you swap out your old plugs for these iridium plugs. They are a great value for the price and come from a company that is known for its quality products.


It’s hard to find any issues with these plugs. One downside is that the plugs may fall out of their packages during shipping, which may cause them to break. Also, while they work great on some vehicles, they're not designed to work on all makes and models.

Honorable Mention

These racing spark plugs are designed to boost fuel economy, provide smooth acceleration, and enable quick starts. They are leakproof and feature a 100 percent copper core for durability and to improve heat transfer. They have multi-rib insulators to prevent misfires and are designed to work with performance modifications.


Your bike will start quicker and will run noticeably better once you install these plugs. They give your bike a boost of power and provide good gas mileage. Overall, your bike will feel more responsive. In addition, you can use these plugs in lawnmowers, leaf blowers, generators, and ATVs.


However, there have been some complaints that these plugs are a little overpriced and that there is little difference in performance compared to some brands of iridium plugs, such as NGK.

Honorable Mention

The NGK 7090 is an excellent all-around spark plug that features a few characteristics which separate it from the others. This plug features a 98% pure copper core with a single-platinum tip. The platinum is much more resistant than copper and makes for a much cooler, longer-lasting plug.


But what makes this a great plug aren't just the elements it features, but how it puts them to work. The use of laser platinum is present to match the manufacturer's specific needs. Rather than trying to make dramatic changes, the emphasis on meeting specifications preserves factory quality. Using a trapezoidal ground strap helps improve performance by reducing quenching, helping the plug maintain the proper temperature. Another notable feature of this plug is the use of alumina-silica ceramic to provide more substantial insulation.


Overall, the quality and construction of the plug are perfect for the average modern daily-driver. But, the information regarding specifications needs some work. Most notably, the application chart isn't that accurate, and you should cross-reference the plug number to ensure it works with your vehicle.

Honorable Mention

ACDelco is known for producing parts that match or exceed the original equipment's quality; these plugs are of no exception. They feature a copper core and double-platinum point pads to provide consistent performance and an extended lifespan. The use of a pure copper core also helps improve performance by maintaining temperature stability that prevents the risk of fouling.


Other notable features of this plug begin with the ceramic insulator. It's hardness rivals that of a diamond and offers excellent strength and shock resistance. The tips rapidly heat up and run hot to keep themselves clean and preserve performance. This plug also has ideal characteristics that maintain the electrode gap, which also aids in maintaining like-new running quality. All of these characteristics, paired with the fact that it's designed to work with older engines, helps once out-of-date vehicles meet today's performance standards.


Like a few others, the specifications can see some improvements. It's listed to work with a litany of applications that it does not. Furthermore, you will need to double-check the gap before installing. This is something you should do regularly, but many reviews report the factory gaps being way off.

Honorable Mention

Here we have a fantastic plug for older vehicles that bode well with a copper plug. The Champion name is one of long-standing favoritism in the segment, particularly by those who stick to American-made cars. The reason is the outstanding performance and reliability no matter the kind of driving the plug is subjected to.


This particular plug does feature a solid copper core. And while that may not be as appealing as those that feature rare metals, it has a distinct advantage in vehicles meant to use this kind of plug. The copper core and nickel-copper alloy electrode offer excellent heat control for superior performance and wear control. There’s no doubt that you will understand why they are found on most American vehicles from the factory when running them.


Copper does have the advantage for plug performance, but there are some considerable drawbacks. Most notably is the short lifespan. Platinum and Iridium plugs last far longer. You should also know that copper plugs are far easier to foul than the others.

Honorable Mention

Here we have a plug designed to meet modern motorists' demands without taking them to the cleaners. This plug has a few design aspects that enhance startup and run quality and promote a longer lifespan than many others. They feature the durability necessary for running 100,000 miles and are backed by a five-year guarantee.


The most notable characteristic of the plug is that it uses a double-platinum layout to promote a long and healthy lifespan. This design offers much better resistance to wear and enhanced heat control that prevents fouling. One thing that really helps this plug perform is the necked-down center electrode. This feature enables the plug to fire much easier to aid in starting and acceleration.


It seems to be a trend for sellers to specify that the plugs work for vehicles that they do not. It’s wise to check the specs of this plug and compare them to your car before purchasing. And as with many others, you must double-check the gap once you get the plugs because the packaging doesn’t offer total protection.

Honorable Mention

The Denso Iridium spark plug does a lot to help the motorist. It’s explicitly designed to improve performance, which is a big demand for any vehicle today. But because it relies on iridium, it also provides a long lifespan to help reduce maintenance requirements and costs.


The iridium helps this plug last far longer than platinum and copper plugs, but that’s no surprise. It’s the tapered electrode that helps this plug meet the demands of performance. The shape of the electrode makes for much easier startups and improvements in acceleration. You may also see some slight improvements in fuel economy as well because of the temperature control.


The major drawback to these plugs is the price. As we know, iridium plugs last longer and cost quite a bit more than other types of plugs. However, this is something that is offset by the reduction in the need to replace the plugs. That ultimately means they cost less in the long run.

Honorable Mention

It might not be a surprise that Bosch is entering our list again with one of the longest living plugs out there. The double-platinum design helps these plugs last up to four times longer than conventional options. But we should say that Bosch has outdone themselves by ensuring everything will help it live nearly as long as the vehicle.


We’ll start by highlighting the essential details. Again, it uses a double-iridium design to maximize reliability, heat control, and wear resistance. But to aid in performance, an ultra-thin .6mm tip is present. That tiny tip makes for a hotter yet easier ignition to boost performance. It’s got a ribbed insulator that helps to prevent misfires as well. And you can’t look past the nickel-plated shell that offers total corrosion-resistant and ant-seize properties.


It’s safe to say that most motorists will sell their vehicles before they ever change the plugs again. But that does come at a cost. As you can expect, these plugs are attached to a premium price point. And because there are more affordable options that last well past 100,000 miles, many may skip these altogether.   

Why Trust Us


All of our reviews are based on market research, expert input, or practical experience with most products we include. This way, we offer genuine, accurate guides to help you find the best picks.

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Benefits of Spark Plugs

  • Increase fuel efficiency. If your engine is powered by worn-out spark plugs, it will not run as efficiently as intended. When you replace these faulty plugs with a set of fresh plugs, your engine will run smoothly and require less effort to keep the combustion process going. This will translate into increased fuel efficiency over the long run.
  • Improve acceleration and engine response. If you notice that your ride isn’t as peppy as it usually is when you step on the gas pedal, you may need to replace your spark plugs. Healthy spark plugs maximize the combustion process in your engine, giving you smooth, responsive acceleration.
  • Smoother engine idle. Fully functioning spark plugs provide sufficient ignition to spur the combustion process in your motor. When spark plugs become faulty, they cause your engine to run rougher than usual, which results in symptoms such as a rough idle. Replacing tired plugs with a set of new plugs will smooth out your idle.
  • Reduce the risk of damage to your engine and other components. Faulty spark plugs can cause misfires, poor fuel economy, lackluster acceleration, and other issues with your ignition system. Left unaddressed, malfunctioning plugs can also cause damage to other components such as your catalytic converter, so it’s vital that you immediately replace bad plugs.
  • Enhanced reliability. If you’re experiencing difficulties starting your car, truck, or SUV, your spark plugs may need to be replaced. Spark plugs are a crucial electrical component necessary to start your vehicle, so inspect your plugs if you’re having trouble getting your ride running.

Types of Spark Plugs

Copper

Copper core spark plugs are the most basic and affordable type of spark plug that you can buy. These used to be the most common plug type on the market, but have recently been replaced by platinum and iridium spark plugs due to their superior performance, efficiency, and lifespan. While many modern engines simply cannot run copper spark plugs, there are a number of older engines that run better using copper plugs. 

Platinum

Platinum plugs deliver enhanced performance and fuel efficiency compared to copper plugs, but for a considerably cheaper price than iridium spark plugs. Much like iridium plugs, platinum spark plugs operate at a lower temperature than copper spark plugs. They can also last up to twice as long as basic copper plugs.

Double-Platinum

Double-platinum spark plugs provide even more performance, efficiency, and longevity than single-plated platinum plugs. What’s more, double-platinum plugs are still typically cheaper than iridium spark plugs. For an affordable upgrade from single platinum, just look for spark plugs that use platinum in both the electrode and cap.

Iridium

The best spark plugs on the market boast an iridium construction. Iridium spark plugs give you even better gas mileage, performance, reliability, and longevity than double-platinum plugs. Due to the advanced material and innovative technology integrated into iridium spark plugs, these plugs are priced higher than copper and platinum options. Iridium spark plugs are perfect to use on high-performance engines.

Top Brands

ACDelco

Founded in 1916, ACDelco is a Grand Blanc, Michigan-based automotive parts brand owned by General Motors. Offering everything from air conditioning components to batteries, ACDelco is perhaps best known for its line of spark plugs. One of its top products is the ACDelco 41-993 Professional Iridium Spark Plug

Bosch

Established in 1886, Robert Bosch GmbH, or simply Bosch, is a massive multinational engineering and electronics company with its headquarters near Stuttgart, Germany. Bosch manufactures a vast diversity of goods, from home appliances to auto parts. One of its best-selling products is the Bosch 6702 Platinum Spark Plug

NGK

Operating from Nagoya, Japan, NGK Spark Plug Co., Ltd. is a public company tracing its roots back to 1936. NGK is best known for its range of spark plugs, though it also manufactures fine ceramics, cutting tools, and more. One of this brand’s popular products is its 6619 Iridium IX Spark Plug.

Spark Plug Pricing

  • Under $3: There are several spark plugs available in this value-priced range. Buyers must do their homework before purchasing cheaper spark plugs due to the vastly varying degree of quality.
  • $3-$9: The majority of spark plugs fall into this pricing segment. Most shoppers choose a spark plug priced in this range because they tend to offer an ideal blend of efficiency, longevity, performance, and value.
  • Over $9: Spark plugs priced in this range tend to feature a durable construction using premium materials, advanced electrode designs, and unparalleled performance, efficiency, and longevity.

Key Features

Material

When you’re shopping for spark plugs, it’s important to consider which material best suits your needs. Copper is ideal for older model vehicles that feature a low-voltage distributor-based ignition. Platinum and iridium are best suited for modern engines without distributors. Platinum delivers a great mix of economy, performance, and longevity. Iridium offers an even better mix but at a higher cost. In the end, always use the plug specified by your vehicle’s manufacturer.

Size

One important way that spark plugs are specified is by the size of the thread or nut. In the United States, typical thread and nut sizes are as follows: 10mm (nut: 16mm), 12mm (nut: 14mm, 16mm, or 17.5mm), 14mm (nut: 16mm or 20.63mm), and 18mm (nut: 20.63mm). 

Heat Range

A spark plug is specified as “hot” if it’s a better heat insulator, and it’s classified as “cold” if it can conduct more heat out of the tip and lower its temperature. Generally, manufacturers denote the heat range of a spark plug with a number, with some brands using ascending numbers for hotter plugs and others doing the opposite for colder spark plugs.

Gap Style

Spark plugs are usually engineered to have a spark gap which can be adjusted using a spark plug gapper tool. A single plug may be designed for several different engines, necessitating a different gap for each. Spark plugs for cars typically gap between 0.6 and 1.8mm (0.024 and 0.071 inches). Use a gap gauge to measure the plug’s gap to ensure that it’s within the specified range. 

Other Considerations

  • User-Friendliness: Some spark plugs come “pre-gapped” right out of the box and does not require adjustment. These pre-gapped spark plugs are convenient and ideal for consumers looking for a plug-and-play style plug that doesn’t require fussing with a gap gauge and tool during installation. If you have some experience turning a wrench, this may not be a huge deal though.  

Best Spark Plug Reviews & Recommendations 2020

Best Overall
NGK 6619 Iridium IX Spark Plugs

The NGK 6619 Iridium IX Spark Plugs snags the top pick in our spark plug comparison because they offer the best mix of high-performance, fuel efficiency, durability, and dependability. Featuring an iridium construction, these high-quality spark plugs provide a longer lifespan than copper and platinum spark plugs.


Their ultra-fine electrode wire promises superior fuel efficiency as well as silky-smooth engine idle and response. You can also expect a healthy boost in power and torque thanks to the optimal air-fuel mixture that these iridium spark plugs generate. They receive top marks for durability with such impressive features as metal plating to resist corrosion and seizing, as well as a long insulator nose to prevent fouling. 


We were hard pressed to come up with any cons for these spark plugs, but if we had to ding them for something, it would be their rather expensive price per spark plug. This higher price may seem like a big ask for more frugal motorists, but the exquisite quality and peerless performance that the NGK 6619 spark plugs deliver make them well worth their cost.

Best Value
Denso 4504 PK20TT Platinum Spark Plugs

If you’re in the market for solid all-around spark plugs that are easy on your wallet, look no further than the Denso 4504 PK20TT Platinum Spark Plugs. These value-priced platinum plugs pack a whole lot of performance, efficiency, and durability for a downright reasonable price.


Featuring a dual-platinum construction with a platinum disc and platinum electrode tip, these spark plugs provide a reliable spark to generate smooth, reliable combustion of the air-fuel mixture. This translates to great engine dependability, fuel efficiency, and performance. Another impressive feature is purified alumina powder, which is used as an insulator to increase thermal conductivity for maximum longevity. 


However, there are a few faults that we found with these double-platinum spark plugs. Occasionally, the gap is incorrectly set on some of the plugs. This is why it’s critical that you inspect the gap and adjust it accordingly. In addition, these double-platinum plugs cannot match the quality, performance, and longevity that iridium spark plugs boast. Nonetheless, we believe that Denso 4504 PK20TT Platinum Spark Plugs are some of the best affordable spark plugs for your car, truck, or SUV. 

Most Reliable
Bosch ZGR6STE2 Copper with Nickel Spark Plug

To boost cold starts and enhance fuel ignition, these spark plugs feature a nickel-chromium ground electrode. They have heavy-duty yttrium enhanced copper core center for optimum performance, reliability, and heat transfer.


These plugs are very durable and have a long lifespan. The nickel-plated shell provides anti-seize and corrosion protection. No gapping is required, and the plug's ribbed insulator prevents flashover. The plugs remedy misfires in certain vehicles, can increase mileage in some vehicles, and may boost performance by a noticeable amount.


One issue with these plugs is they may not fit certain vehicles even though the specs indicate that they will. They may also be shipped in non-padded boxes with the plugs rolling around loosely in the package, which could damage them. Another problem is while the gap is set at the factory, they still may need to be slightly adjusted.

Most Durable
Bosch X5DC Copper with Nickel Spark Plug

This OE replacement plug has a long lifespan and is very durable. The iridium firing pin is welded with a 360-degree continuous laser, and the copper core is designed to reduce fouling. 


The wire is ultra-fine, and the nickel-plated shell prevents it from seizing. No gapping is required, and the plug has corrosion protection. One of the best things about these plugs is they last a long time, which is important if you have an engine in which the plugs are difficult to access. While you may not notice a change in mileage after you install them, you may see a boost in performance. They are also very reliable, and you don't need a special gap tool for installation.


However, they are not compatible with all vehicles, so you need to double-check the gap to see if they will fit your make and model. Also, there have been some complaints that the boxes get damaged during shipping, and the plugs roll around loosely, which can potentially damage them.

Honorable Mention
NGK 4929 Standard Spark Plug

The NGK 4929 spark plug for motorcycles and UTVs has a solid copper core for more spark and a long insulator nose to minimize fouling. It's dipped in zinc to prevent corrosion and features insulators with corrugated ribs to reduce flashover. To eliminate gas leakage, the plug has a triple gasket seal.


These plugs work well on a variety of bikes, including Suzukis, Triumphs, and Honda Recon 250s, among others. They work as expected and keep your bike running well in temperatures as low as 24-degrees Fahrenheit or as high as 100-degrees Fahrenheit. Overall, they have clean, crisp threads and are easy to install.


However, they won't fit on all bike models. Also, while they're a decent price, you may be able to find a cheaper alternative. In addition, the plugs don’t come with screw-on caps, which you may need for certain applications.

Honorable Mention
NGK BKR7EIX Iridium IX Spark Plug

NGK's Iridium IX spark plug is designed to boost throttle response and prevent fouling. Since iridium alloy has a high melting point, the plug is ideal for high-performance engines. It features a 0.6mm laser-welded fine iridium tip for a longer lifespan and a stable spark. It's designed to reduce and prevent flashover, combustion gas leakage, and electrical quenching. 


The plugs have anti-corrosion and anti-seizing characteristics. It's common for a vehicle to exhibit an improvement in acceleration and a slight increase in gas mileage after installing these plugs. They are simple to install, and your vehicle will run smoother and more efficiently. Overall, they're great for turbocharged and supercharged cars.


The biggest problem with these plugs is that you may need to regap them for proper installation. Some consumers have also complained that they've noticed no change in performance after installing them.

Honorable Mention
<strong>ACDelco 41-103 Professional Iridium Spark Plug</strong>

This plug is ideal for performance-driven vehicles as well as older vehicles that need conventional plugs. ACDelco boasts that these plugs can last up to 100,000 miles, depending on the application. The iridium tip minimizes spark erosion, and it's designed to prevent compression leakage. The plug also increases fuel efficiency because the spark gap stays nearly the same during its lifespan.


The plugs come perfectly gapped for certain makes and models, such as Chevy and GM vehicles. You will notice a difference in startup and performance after you swap out your old plugs for these iridium plugs. They are a great value for the price and come from a company that is known for its quality products.


It’s hard to find any issues with these plugs. One downside is that the plugs may fall out of their packages during shipping, which may cause them to break. Also, while they work great on some vehicles, they're not designed to work on all makes and models.

Honorable Mention
E3.36 Power Sport Spark Plug

These racing spark plugs are designed to boost fuel economy, provide smooth acceleration, and enable quick starts. They are leakproof and feature a 100 percent copper core for durability and to improve heat transfer. They have multi-rib insulators to prevent misfires and are designed to work with performance modifications.


Your bike will start quicker and will run noticeably better once you install these plugs. They give your bike a boost of power and provide good gas mileage. Overall, your bike will feel more responsive. In addition, you can use these plugs in lawnmowers, leaf blowers, generators, and ATVs.


However, there have been some complaints that these plugs are a little overpriced and that there is little difference in performance compared to some brands of iridium plugs, such as NGK.

Honorable Mention
NGK 7090 BKR5EGP G-Power Spark Plug

The NGK 7090 is an excellent all-around spark plug that features a few characteristics which separate it from the others. This plug features a 98% pure copper core with a single-platinum tip. The platinum is much more resistant than copper and makes for a much cooler, longer-lasting plug.


But what makes this a great plug aren't just the elements it features, but how it puts them to work. The use of laser platinum is present to match the manufacturer's specific needs. Rather than trying to make dramatic changes, the emphasis on meeting specifications preserves factory quality. Using a trapezoidal ground strap helps improve performance by reducing quenching, helping the plug maintain the proper temperature. Another notable feature of this plug is the use of alumina-silica ceramic to provide more substantial insulation.


Overall, the quality and construction of the plug are perfect for the average modern daily-driver. But, the information regarding specifications needs some work. Most notably, the application chart isn't that accurate, and you should cross-reference the plug number to ensure it works with your vehicle.

Honorable Mention
ACDelco 41-962 Professional Platinum Spark Plug

ACDelco is known for producing parts that match or exceed the original equipment's quality; these plugs are of no exception. They feature a copper core and double-platinum point pads to provide consistent performance and an extended lifespan. The use of a pure copper core also helps improve performance by maintaining temperature stability that prevents the risk of fouling.


Other notable features of this plug begin with the ceramic insulator. It's hardness rivals that of a diamond and offers excellent strength and shock resistance. The tips rapidly heat up and run hot to keep themselves clean and preserve performance. This plug also has ideal characteristics that maintain the electrode gap, which also aids in maintaining like-new running quality. All of these characteristics, paired with the fact that it's designed to work with older engines, helps once out-of-date vehicles meet today's performance standards.


Like a few others, the specifications can see some improvements. It's listed to work with a litany of applications that it does not. Furthermore, you will need to double-check the gap before installing. This is something you should do regularly, but many reviews report the factory gaps being way off.

Honorable Mention
Champion RC12YC Spark Plug

Here we have a fantastic plug for older vehicles that bode well with a copper plug. The Champion name is one of long-standing favoritism in the segment, particularly by those who stick to American-made cars. The reason is the outstanding performance and reliability no matter the kind of driving the plug is subjected to.


This particular plug does feature a solid copper core. And while that may not be as appealing as those that feature rare metals, it has a distinct advantage in vehicles meant to use this kind of plug. The copper core and nickel-copper alloy electrode offer excellent heat control for superior performance and wear control. There’s no doubt that you will understand why they are found on most American vehicles from the factory when running them.


Copper does have the advantage for plug performance, but there are some considerable drawbacks. Most notably is the short lifespan. Platinum and Iridium plugs last far longer. You should also know that copper plugs are far easier to foul than the others.

Honorable Mention
Autolite APP5325-4PK Double Platinum Spark Plug

Here we have a plug designed to meet modern motorists' demands without taking them to the cleaners. This plug has a few design aspects that enhance startup and run quality and promote a longer lifespan than many others. They feature the durability necessary for running 100,000 miles and are backed by a five-year guarantee.


The most notable characteristic of the plug is that it uses a double-platinum layout to promote a long and healthy lifespan. This design offers much better resistance to wear and enhanced heat control that prevents fouling. One thing that really helps this plug perform is the necked-down center electrode. This feature enables the plug to fire much easier to aid in starting and acceleration.


It seems to be a trend for sellers to specify that the plugs work for vehicles that they do not. It’s wise to check the specs of this plug and compare them to your car before purchasing. And as with many others, you must double-check the gap once you get the plugs because the packaging doesn’t offer total protection.

Honorable Mention
Denso (3297) SK20R11 Iridium Spark Plug

The Denso Iridium spark plug does a lot to help the motorist. It’s explicitly designed to improve performance, which is a big demand for any vehicle today. But because it relies on iridium, it also provides a long lifespan to help reduce maintenance requirements and costs.


The iridium helps this plug last far longer than platinum and copper plugs, but that’s no surprise. It’s the tapered electrode that helps this plug meet the demands of performance. The shape of the electrode makes for much easier startups and improvements in acceleration. You may also see some slight improvements in fuel economy as well because of the temperature control.


The major drawback to these plugs is the price. As we know, iridium plugs last longer and cost quite a bit more than other types of plugs. However, this is something that is offset by the reduction in the need to replace the plugs. That ultimately means they cost less in the long run.

Honorable Mention
Bosch 9614 Double Iridium OE Replacement Spark Plug

It might not be a surprise that Bosch is entering our list again with one of the longest living plugs out there. The double-platinum design helps these plugs last up to four times longer than conventional options. But we should say that Bosch has outdone themselves by ensuring everything will help it live nearly as long as the vehicle.


We’ll start by highlighting the essential details. Again, it uses a double-iridium design to maximize reliability, heat control, and wear resistance. But to aid in performance, an ultra-thin .6mm tip is present. That tiny tip makes for a hotter yet easier ignition to boost performance. It’s got a ribbed insulator that helps to prevent misfires as well. And you can’t look past the nickel-plated shell that offers total corrosion-resistant and ant-seize properties.


It’s safe to say that most motorists will sell their vehicles before they ever change the plugs again. But that does come at a cost. As you can expect, these plugs are attached to a premium price point. And because there are more affordable options that last well past 100,000 miles, many may skip these altogether.   

Tips

  • Have your vehicle information handy when shopping for new plugs to ensure you purchase the right spark plugs for your ride. Your owner’s manual or vehicle registration card should have the following information: model year, make, model, engine displacement, carburetor or fuel injection type, and cylinder count.   
  • It’s a wise idea to replace your spark plug wires when you change your plugs. Faulty spark plugs can damage the wires, so swapping out both components at the same time will ensure that your engine receives the best ignition parts possible.
  • As tempting as it is, don’t always purchase the least expensive option for spark plugs. The best-quality spark plugs are usually more expensive because they guarantee optimal fuel economy, engine performance, longevity, and reliability.
  • Inspect your plugs to determine their condition. If the plugs look fine except for a red coating, this could be residual additives from poor-quality gas. Clean them off with a clean cloth and reinstall them. If the plug has black or heavy ash deposits around or on top of its center electrode, this means it must be replaced.
  • Before you remove your old plugs, clean the cylinder head around your plugs with a compressed air can or gun. This will blow away any dirt or deposits that may have collected in this area. This is important because dirt can enter the cylinder bore and score the wall and wear the rings.
  • Inspect the new spark plugs for any damage. Ensure the side electrode aligns with the center electrode and is straight. If any adjustment is required, use needle-nose pliers to gently reposition it. 
  • With the plug positioned downwards, spray the cavity around the center electrode with carburetor cleaner. This is an effective method to remove any porcelain dust or debris left over from the manufacturing process that can cause misfires.
  • Use an anti-seize compound to coat the spark plug thread. This will make it easier to remove the plug in the future without galling the threads in the cylinder head. If any of the anti-seize compound happens to get on the electrodes, wipe it off with a clean rag moistened with carburetor cleaner. 
  • Use a dielectric compound to coat the secondary wire connection and the insulator where the boot sits. The dielectric compound prevents corrosion and prevents the boots from sticking to the insulator, which can cause the wires to break during future maintenance. 
  • Never use air tools to remove or install spark plugs in your vehicle. Always thread each spark plug by hand, and then use a proper socket and wrench to tighten the plugs according to factory specifications.

FAQs

Should I use hot or cold spark plugs?

A: In typical driving circumstances, you should use the spark plugs specified by your vehicle’s manufacturer. A hot plug may be a good option if your spark plugs are fouled from carbon deposits, your engine has a rich air-fuel ratio or burns oil, or if you do a lot of local low-speed driving. If your engine is pinging, has a lean air-fuel ratio, or if you do a lot of high-speed driving, consider a cold plug.

How frequently should I change my spark plugs?

A: This depends on the quality of spark plugs you have in your car. Top-quality spark plugs will last longer than lower-quality plugs. Most mechanics recommend you change your copper core spark plugs every 30,000 miles or every 50,000 miles for iridium core spark plugs. This interval may be shorter if your engine isn’t in top condition, so it’s vital to inspect your spark plugs for premature wear and change them accordingly.

What are the symptoms of a faulty spark plug?

A: You may notice the following symptoms if your spark plugs need to be replaced: hesitation or backfiring during acceleration, decreased acceleration, rough idle, spark plug wires charred on the end that goes onto the plugs, a significant drop in fuel economy, and difficulties starting your engine. If your ride doesn’t run as well as it usually does, and you suspect it’s attributed to bad spark plugs, inspect the plugs yourself or have a mechanic do it.

Can I clean my spark plugs?

A: Yes, you can clean your spark plugs, but it’s generally not recommended. When you clean a spark plug using a wire brush or sturdy knife to scrape off the deposits, it can dull it and drastically lower its efficiency. If you insist on cleaning your spark plugs, use a spray-on plug cleaner specifically engineered for this vital component. 

Do unopened spark plugs have a shelf life?

A: As long as unopened spark plugs are properly stored in a dry, cool environment, then they should last an indefinite amount of time. The lifespan of spark plugs is impacted only when they are exposed to corrosive environmental factors such as moisture or if they’re dropped frequently.

Final Thoughts

Our first place pick for the best spark plugs on the market is the NGK 6619 Iridium IX. These iridium plugs will deliver unbeatable engine performance, fuel efficiency, longevity, and protection from misfires and malfunctions.

If you’re looking for value-priced plugs offering some serious performance, the Denso 4504 PK20TT Platinum Spark Plugs will do nicely.