The 10 Best Spark Plugs

Only the best spark plugs will give your engine the jolt it needs to operate efficiently, effectively, and reliably.

For something so small and inconspicuous, spark plugs sure do play an integral role in a vehicle’s operations. They are, after all, what “sparks” your car to life.

If you’re looking for a replacement, our review catalog and buying guide highlight some of the best spark plugs on the market and teach you how to find the right ones for your car. Here is a quick rundown of our top picks.

Best Spark Plugs Reviews

We found and reviewed 10 great spark plugs to make your life easier. The criteria we used to select each one can be found in the buyer’s guide section.

1. NGK 6619 Iridium Spark Plugs

Despite being on the expensive end of the price spectrum, the NGK 6619 Iridium IX Spark Plugs deliver the best combination of performance, efficiency, and durability. 

As indicated by their name, these spark plugs have an iridium construction, meaning they last longer than copper and platinum spark plugs.

Each one boasts an ultra-fine electrode wire that promises a responsive, smooth idling engine and improved fuel efficiency, while the excellent air-fuel mixture they help generate provides a nice boost in power.

The NGK 6619 Iridium IX Spark Plugs are also built tough, thanks in large part to their metal plating that resists corrosion and seizing, and long insulator nose that prevents fouling. 

Bottom Line

The unprecedented combination of quality, performance, and efficiency of the NGK 6619 Iridium Spark Plugs makes them worth their high price tag. CHECK LATEST PRICE

2. Denso 4504 Platinum TT Spark Plug

The Denso 4504 Platinum TT Spark Plug is a solid all-around option with a reasonably affordable price.

These highly-rated spark plugs feature a dual-platinum construction that uses a platinum disc and a platinum electrode tip to generate smooth and reliable combustion. 

Although they are not as capable as iridium spark plugs, you can expect great performance, efficiency, and dependability out of your engine.

Another noteworthy feature of the Denso 4504 Platinum TT Spark Plugs is that they use a purified alumina powder as an insulator to increase thermal conductivity, which should increase their lifespan.

They come pre-gapped, making them easier to install. Unfortunately, the gap can sometimes be incorrectly set on some units, so inspect the gap and make any necessary adjustments before using them.

Bottom Line 

For a very reasonable price, the Denso 4504 Platinum TT Spark Plug offers a level of performance, efficiency, and durability that won’t leave most people wanting. CHECK LATEST PRICE

3. NGK 7090 BKR5EGP G-Power Spark Plug

This platinum spark plug tries to provide the performance of iridium plugs for a cheaper price, and it succeeds for the most part.

A 0.6mm laser welded fine Platinum tip reduces the voltage required to create a spark, ensuring high durability and consistently stable sparks, while a corrugated insulator nose helps enhance throttle response and minimize flashovers. 

The NGK 7090 BKR5EGP G-Power Spark Plug also boasts trivalent metal plating for superior anti-corrosion and anti-seizing properties, as well as a triple gasket seal that eliminates combustion gas leakage.

You can expect it to run for at least 100,000 miles (160,934 km) before needing to be replaced, a lifespan that would have been longer if platinum was used elsewhere other than at just the tip.

Bottom Line 

The NGK 7090 BKR5EGP G-Power Spark Plug may not be an iridium plug, but it offers a lot of performance for a relatively low price. CHECK LATEST PRICE

4. Bosch 9607 Double Iridium Spark Plug

Considering the superlative performance iridium tech provides, it’s no surprise that yet another iridium spark plug made our list of best spark plugs.

The Bosch 9607 Double Iridium Spark Plug boasts a double Iridium firing pin and ground electrode inlay that makes it more durable than platinum and copper plugs, offering a lifespan that’s four times longer than the latter, 

This spark plug is so durable, in fact, that it can last up to 7 years before needing to be replaced.

A 0.6mm fine wire firing pin provides superior ignitability and performance, while a nickel-plated shell makes it corrosion-resistant. For added convenience, each plug comes with a pre-gapped fit and there is no need for anti-seize lubrication.

Of course, the fact that iridium generally provides the best performance, efficiency, and durability means the Bosch 9607 Double Iridium Spark Plug is pricier than most copper and platinum plugs.

Bottom Line

Few spark plugs can exceed the Bosch 9607 Double Iridium Spark Plug in performance, efficiency, and durability. CHECK LATEST PRICE

5. NGK 4929 Standard Spark Plug

Whether you own a high-performance sports car, a minivan, or an off-road vehicle, the NGK 4929 spark plug will do your vehicle justice. That’s because it works well on all manners of vehicles, including many motorbikes.

This spark plug uses a solid copper core to achieve more spark and a longer-than-usual insulator nose to prevent fouling, engine misfires, and rough idling. 

The shell is coated in zinc to keep corrosion at bay, while corrugated ribs reduce the risk of flashover. A triple gasket seal eliminates gas leakage.

The NGK 4929 Spark Plug also happens to have a very decent price. However, it doesn’t come with screw-on caps, a feature certain applications require.

Bottom Line

The NGK 4929 Standard Spark Plug delivers an incredible spark, as well as great value. CHECK LATEST PRICE

6. Bosch X5DC Copper With Nickel Spark Plug

The Bosch X5DC Copper with Nickel Spark Plug has several advanced features that make it one of the highest performing spark plugs on the market.

For starters, it features a yttrium enhanced center electrode that reduces oxidation, as well as a Ni/Cr ground electrode that improves fuel ignitability and cold starts.

This long-lasting spark plug also utilizes a corrugated insulator nose to reduce flashovers and improve the throttle, while its factory set gapping allows you to install it right out of the box. 

At the same time, rolled threads of its nickel-plated shell prevent seizing, while ultra-fine wiring results in less required voltage for getting the engine up and running.

The Bosch X5DC Copper with Nickel Spark Plug is truly capable, but it’s pricey and not compatible with every vehicle. You will have to double-check the pre-set gap to make sure it fits your car’s engine.

Bottom Line

The Bosch X5DC Copper with Nickel Spark Plug has the performance and longevity to back its higher price tag. CHECK LATEST PRICE

7. Denso 5304 IK20 Iridium Power Spark Plug

The Denso 5304 IK20 Iridium Power Spark Plug is three times more expensive than some of the other plugs on this list, so you’d expect it to pack a lot of performance, right? It does!

As a premium product, these plugs come with iridium tips and an incredible 0.4 mm wide electrode, translating to excellent performance, efficiency, and longevity.

After all, iridium is the best material for spark plugs, and the thinner a plug’s electrode is, the higher its performance.

The Denso 5304 IK20 Iridium Power Spark Plug is indeed one of the best spark plugs, even with its high price tag.

Bottom Line

The Denso 5304 IK20 Iridium Power Spark Plug matches its premium price with premium performance. CHECK LATEST PRICE

8. Champion RE14MCC4 (570) Copper Plus

Don’t be quick to write off copper spark plugs because they use old tech. A model like the Champion RE14MCC4 (570) Copper Plus still has a place in today’s automotive world, seeing as there are still some cars that can only use copper spark plugs.

Yes, this basic spark plug is a far cry from cutting-edge tech, but it is nicely put together and has built-in anti-corrosion resistance.

Not only is it effective and dependable, but it’s also affordable — the cheapest spark plug on our list, in fact.

Simply put, the Champion RE14MCC4 (570) Copper Plus is one of the greatest values on the market. It is the very representation of the ‘effectiveness of simplicity’ concept.

Bottom Line

If your car only uses copper spark plugs, the Champion RE14MCC4 (570) Copper Plus is an excellent option. CHECK LATEST PRICE

9. ACDelco 41-962 Professional Platinum Spark Plug

The ACDelco 41-962 Professional Platinum Spark Plug is well-loved for its ability to deliver smoother engine starts and improved acceleration. As a double platinum plug, it’s also more durable and longer-lasting than copper and single platinum plug.

Its tip heats up to burn off carbon deposits that can potentially interfere with the sparks, while its platinum center electrodes were designed to consume the least amount of power possible to generate a spark. 

Often purchased for old and new General Motors vehicles such as the Chevrolet Silverado and GMC Sierra pickup trucks, the ACDelco 41-962 Professional Platinum Spark Plug was designed to meet or exceed original part specifications. 

However, with a price that matches some iridium plugs, it’s pretty expensive for a platinum spark plug.

Bottom Line

If you have an old or new GM vehicle, the ACDelco 41-962 Professional Platinum Spark Plug is bound to work wonders. CHECK LATEST PRICE

10. Autolite APP104 Double Platinum Spark Plug

The Autolite APP104 Double Platinum Spark Plug makes no pretense of being a premium product. What you get instead is a superb everyday spark plug for normal cars.

It features a full platinum tip, with platinum applied on both the center and side electrodes to reduce gap wear and improve longevity.

The center electrode is positioned neck-down so that it fires quicker and cleaner for easier starts, quicker acceleration, and improved fuel economy, while a nickel-plated steel shell prevents corrosion.

The Autolite APP104 Double Platinum Spark Plug is not a performance powerhouse, but it works well and reliably enough on most cars.

Bottom Line 

If you have a normal car that you use to do normal things, the Autolite APP104 Double Platinum Spark Plug won’t disappoint. CHECK LATEST PRICE

Spark Plug Buying Guide

Shopping for spark plugs can be quite difficult. With dozens of choices available, how can you be sure you’ve picked the best spark plugs for your car? 

Our detailed, expert researched guide provides everything you need to know.

What Is A Spark Plug?

When you start up your car, it’s the spark plugs that literally ‘spark’ your engine to life. 

These little devices ignite the combustion process, keeping your engine humming, and setting your car in motion.

Basically, without spark plugs, your car wouldn’t be able to start up, forcing you to find alternative methods to get to your destination.

How Do Spark Plugs Work?

For an internal combustion engine to run, fuel (gasoline, diesel, etc.) and air must combust to release energy. And for this combustion to happen, there needs to be a spark.

That ‘spark’ is provided by — you guessed it — spark plugs. 

These little devices emit tiny electrical sparks within the combustion chamber (cylinder head) of the engine to ignite the controlled ‘explosion’ required to move the pistons. 

View spark plugs as a matchstick or lighter that start up the fire in your engine, setting the pistons in motion and delivering a smooth burn of compressed air-fuel mixture to keep your car running.

Benefits of Spark Plugs

Spark plugs do more than just provide the spark necessary to get your car moving. The following are five other key benefits of spark plugs.

Improve Acceleration

Quality spark plugs help ensure smooth and energetic starts that let your car accelerate faster and more assuredly.

Smooth Engine Idle

If your car is shaking, bouncing, and/or making strange noises when idling, then your spark plugs might be poorly installed or damaged. Quality, well-designed spark plugs work optimally with your engine to deliver smoother engine idling. 

Improve Fuel Efficiency

According to The National Institute for Automotive Service Excellence, misfiring spark plugs can reduce your car’s fuel efficiency by 30% or more. Quality spark plugs, therefore, will improve your fuel efficiency and save you money. 

Less Harmful Emissions

A study by the EPA found that not only do regular engine tune-ups involving spark plugs save gas, but they also greatly reduced air pollution.

Prevent Engine Damage

Faulty or worn-out spark plugs can cause engine misfires, poor acceleration, bad fuel economy, and other issues that put undue strain on your engine’s components, potentially causing damage and necessitating expensive repairs.

Types of Spark Plugs

There are four main types of spark plugs: copper, platinum, double-platinum and iridium. Each has advantages and disadvantages depending on the vehicle they are used on.

Copper Spark Plugs

Copper spark plugs are mostly made from solid copper and have a  nickel alloy central electrode. These spark plugs are the least sophisticated and, therefore, most affordable type of spark plug. 

Having the largest diameter of all the other spark plugs means they require more voltage to generate an electric current. Moreover, nickel is a soft, delicate, and short-lived alloy,  so you’ll have to replace the spark plugs more frequently than other types.

Once commonplace in the market, copper spark plugs are now mostly found in old cars, having been replaced by the more durable platinum, and iridium spark plugs.

Platinum Spark Plugs

Single-platinum spark plugs have a similar design to copper spark plugs but feature a platinum disc welded to the tip instead of just a nickel alloy central electrode 

Platinum is a far more durable metal than nickel, explaining why platinum plugs can last over twice as long as basic copper plugs. They are also better able to operate at lower temperatures.

Although more expensive than copper spark plugs, platinum spark plugs are considerably cheaper than iridium spark plugs. 

Double Platinum Spark Plugs

A double platinum spark plug has a platinum coating on both the center and ground electrodes, making it more efficient and longer-lasting than a single-platinum spark plug. 

It also has a ‘waste spark’ design that doesn’t recycle a spark, making it well-suited for wasted spark ignition systems

As you would expect, you pay more for the extra performance, but still not as much as you would for an iridium plug.

Iridium Spark Plugs

Iridium spark plugs are the newest and most advanced type of spark plug. The fact that iridium is a harder, more durable metal than platinum makes them the longest-lasting type you can buy.

Ideal for high-performance engines, these plugs are also designed with a small center electrode that requires less voltage to generate a spark.

Unsurprisingly, many of today’s best spark plugs have an iridium construction. However, their superior performance, efficiency, and longevity mean you’ll have to pay a higher price than double platinum spark plugs.

Top Spark Plug Brands

There are many spark plug brands, but the market is mostly dominated by the following three.

NGK

Founded in 1936 and based in Nagoya, Japan, the NGK Spark Plug Co. manufactures and sells spark plugs, ceramics, and other related products. It is a household name, with the NGK 6619 Iridium IX Spark Plug being one of its most popular products.

Bosch

Robert Bosch GmbH, or Bosch for short, is a German multinational engineering company headquartered near Stuttgart, Germany, that produces a vast array of consumer and industrial goods. The Bosch 6702 Platinum Spark Plug is one of their best-selling products.

ACDelco

ACDelco is an American automotive parts brand founded in 1916. Owned by General Motors, it is best known for producing spark plugs, including the very popular ACDelco 41-993 Professional Iridium Spark Plug.

Features Of The Best Spark Plugs

The following are the essential features of spark plugs that you must consider when shopping for a good set.

Material, Durability

We highlighted the impact certain materials have on the performance and durability of spark plugs in the section discussing the different types of spark plugs. It’s crucial that you consider which material is most compatible with your car.

For instance, copper spark plugs are cheaper but far less efficient, durable, and long-lasting than platinum and Iridium. While you might be tempted to upgrade to one of the other types, doing so may actually worsen your car’s performance if your car was specifically designed to use copper plugs.

Even so, it makes sense to prioritize service life no matter the type of spark plug your car uses. If you have a newer car, you don’t want spark plugs that last less than 20,000 miles (32,187 km).

Size

In the world of spark plugs, size does matter. In fact, it’s one of the key ways these small devices are specified.

If the spark plug is too small or too big for your car, using it would be no better than driving around with an old, worn-out, or even defective plug.

Fortunately, good spark plugs usually have their size specification printed somewhere on them, allowing you to cross-match with your original plugs. Checking your car’s owner’s manual to verify the size is another way to go about it.

Heat Range

A spark plug is considered to have a “hot” heat range if it’s a good heat insulator, while having a “cold” heat range means it can operate in lower temperature conditions and resist heating up too quickly.

Manufacturers usually indicate the heat range of their spark plug with a number. Some use ascending numbers for hotter spark plugs, while others do the opposite for colder plugs.

Gap Style

Spark plugs are designed to have a spark gap, a tiny little space between the center and ground electrodes that you can adjust using a spark plug gapper tool.

It’s fairly common for a single plug to be engineered for several different engines, necessitating different gap settings for each engine.

Tips For Buying Spark Plugs

Here are additional tips to keep in mind when shopping for good spark plugs.

1. Don’t just buy one spark plug. When changing spark plugs, you need to replace all the spark plugs at the same time. Your engine performs best when they all match and have nearly the same levels of electrical resistance.

2. If your vehicle manufacturer recommends that you use a specific size, type, and/or model of spark plug, it would be wise not to deviate, even if your car uses what some would consider an “inferior” type of spark plug.

3. If your vehicle manufacturer doesn’t specify the heat range for the spark plug, it is generally recommended that you go with one that isn’t too hot or too cold. Spark plugs that are too “cold” are less able to burn the deposits that clog the firing end, while those that are too hot can potentially melt the electrode.

4. If you don’t want to waste time adjusting the spark gap during installation, consider getting pre-gapped spark plugs.

5. Splurge on higher-priced spark plugs if you can afford to. The few extra dollars out of your pocket will be worth it if the plugs offer better performance and longevity.

Signs Of Bad Spark Plugs

When your car has trouble starting, the cause might be old or faulty spark plugs, rather than a dead battery. Here are five key signs your spark plugs need to be changed or at the very least inspected.

Engine Misfiring

This occurs when built-up carbon deposits on the spark plugs cause one or more cylinders to misfire, impeding the engine’s performance and increasing emissions.

Trouble Starting Car

Achieving the spark needed to start your engine is difficult if not impossible when the spark plugs are dirty or damaged.

Rough Engine Idle

If you hear weird noises coming out of your car’s engine or if it’s making more noise than usual, get the spark plugs checked.

Slow Acceleration

If you notice that your car isn’t as responsive as normal, particularly when you’re trying to accelerate, you might be dealing with worn spark plugs.

Poor Fuel Economy 

A misfiring spark plug can reduce your fuel efficiency by as much as 30%. That’s because worn-out spark plugs are less effective at igniting the fuel that goes into the engine, resulting in wasted fuel and money.

Engine Surge Or Hesitation

Engine surges are a telltale sign of combustion problems possibly caused by a faulty spark plug. They can be very dangerous, so get your car checked immediately if you’re experiencing them.

How To Change Spark Plugs

You don’t need to be a gearhead to know how to change your car’s spark plugs, nor do you need to pay a mechanic to have them replaced. Here is a step-by-step guide you can follow to do the replacement yourself:

Step 1. Make sure you have the right spark plugs. Remember, not all spark plugs will be compatible with your car’s engine.

Step 2. Locate the spark plugs in your car, and familiarize yourself with their recommended service and replacement procedure. You can do this by reading the vehicle’s owner’s manual. 

Step 3. Making sure that the engine is not hot, carefully disconnect the spark plug wires off the terminals. Accessing these wires may require removing clips, covers, or fasteners. 

Step 4. Using a socket wrench, unscrew and remove the spark plugs.

Step 5. Check to make sure the new spark plugs are not damaged in any way and that they are the same size as your old plug.

Step 6. After determining that the new spark plugs are not damaged and are of the right size, proceed to interest each one. Tighten them using a spark plug socket and a ratchet, but not too tight as to risk damaging the spark plug and engine cylinder head.  

Step 7. Reattach all necessary spark plug wiring, oil packs, clips, or fasteners that you disconnected in Step 3.

Note: Even if only one spark plug is faulty or damaged, it is necessary to change all the spark plugs in the car simultaneously to ensure your engine operates optimally. Repeat the removal and installation process until all of them are replaced.

Spark Plug Maintenance Tips

Spark plugs are so crucial to the operation of an engine that they shouldn’t be neglected. Here are some simple tips for keeping your plugs in optimal condition.

• Clean the old spark plug before removing it so that the dirt or debris it collected doesn’t enter the engine’s cylinder bore.
• Always inspect the new spark plug for damage before installing it. Make sure the electrodes are free of fluids like water and that the side electrode is straight and aligned with the center electrode.
• Position the spark plug downwards and spray the cavity around the center electrode with a carburetor cleaner to remove any leftover dust or debris from manufacturing, which can cause misfires.
• If the spark plug doesn’t have an anti-seizing feature, treating it with anti-seize lubrication will reduce the probability of seizing.
• Any red coating that appears on the spark plugs can be wiped off with a clean cloth. However, the appearance of black or heavy ash means the plugs need to be replaced.
• You can prevent corrosion by applying a dielectric coat to the secondary wires and porcelain insulator. 

Spark Plug FAQs

Here, we answer some frequently asked questions about spark plugs that may not have been answered in the previous sections.

How Many Spark Plugs Are In A Car?

It depends on the number of cylinders an engine has. A car with a four-cylinder engine will have four spark plugs, a six-cylinder car will have six, etc.

Some engines have multiple spark plugs per cylinder, such as the HEMI engine, which has two plugs per cylinder.

How Much Do Spark Plugs Cost?

Despite having one of the most important jobs in an ICE vehicle, spark plugs are incredibly inexpensive. In North America, a single plug often costs less than $10, while a set of plugs can fetch you anywhere from $16 to $100, depending on quality.

Should I Choose Cold Or Hot Spark Plugs?

In normal driving conditions, go with the spark plug heat range directed by your vehicle’s manufacturer.

Cold spark plugs may be a good option for high-performance engines, however, seeing as they produce a large amount of heat, while hot spark plugs may be better for low RPM engines. 

Iridium Vs Platinum Spark Plugs, Which Is Better?

Iridium spark plugs are distinguished by their extremely fine center electrodes and excellent durability. The former attribute ensures fast and reliable ignitions, stable idling, and improved fuel economy, while the latter allows them to last almost twice as long as comparable platinum spark plugs. 

The only drawback of iridium spark plugs is that they cost double the price of platinum plugs without providing double the performance.

Do Iridium Spark Plugs Increase Horsepower?

Iridium plugs can indeed boost your engine’s performance, even if by a slight bit, because they require less voltage to fire. This results in more coil dwell time, which translates to improved combustion, more horsepower, better fuel economy, and lower emissions.

How Frequently Should I Change My Spark Plugs?

Spark plugs should always be changed according to the frequency specified by the vehicle owner’s manual (around 30,000 miles / 48,280 km, usually) or once signs of damage are detected.

If your owner manual doesn’t specify how often you should change your spark plugs, or if you don’t know the last time the spark plugs were installed, seek assistance from an expert. 

The quality of the spark plug plays a role, with most mechanics recommending you change copper core spark plugs every 30,000 miles and iridium core spark plugs every 50,000 miles (80,467 km).

How Much Does It Cost To Replace Spark Plugs?

The average cost of having your spark plugs replaced by a mechanic or service technician can vary depending on your vehicle and location. However, it typically ranges between $40 and $150.

Replacing the spark plugs yourself can be significantly less expensive, and the process is fairly straightforward.

Conclusion

Fully-functioning spark plugs entail a fully-functioning combustion system that delivers optimal all-around performance consistently so that both you and your car never miss a beat.

Now that you are more knowledgeable about spark plugs, how they work, and what happens when they are faulty, make it a priority to have them checked and replaced when necessary.

And remember, not all spark plugs work on every engine. Although the NGK 6619 Iridium IX is our pick for the best spark plugs, they may not be compatible with your car or truck. Always go with the plugs recommended by your vehicle’s manufacturer.