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Published Jul. 16, 2021

Spark plugs may be tiny when they’re held in your hand, but these auto components are absolutely essential to your daily drives. The little spark plug is responsible for your engine’s power — without a spark plug, you can’t fire up your engine and hit the road. It’s this single part that helps vehicles’ internal combustion engines operate. And over many miles on the road, spark plugs can deliver a smooth driving experience and effortless starts. 

However, when spark plugs become worn, they can start to introduce problems. These tiny components can start to cause lagginess, sluggishness, and other woes. Fortunately, all you have to do is swap out your old spark plugs for new ones to get your engine back on track. If it’s a job you’re tackling yourself, we’ve got a list of the best spark plugs you can buy to help you find the perfect fit for your engine.

Best Rated Spark Plugs in 2021:

While iridium is overall the best material to look for in a spark plug, it’s also pretty expensive. Platinum constructed plugs are not a million away in terms of quality and life span, and this model from DENSO is one of the better options on the market right now.

It employs a dual platinum construction, with a platinum disk and platinum electrode tip. The electrode itself has a width of 11mm, which is a little thicker than you will find on truly premium plugs however it’s not going to have a noticeable effect on performance in a normal car in regular driving conditions.

Purified alumina powder is used as an insulator material too, which increases thermal conductivity and should help provide a long working life span. This item packs in quite a lot of features into a relatively small price tag. Well done, DENSO.

Key Features
  • Platinum Twin Tips
  • Advanced Materials
Specification
  • Brand DENSO
  • Model PK20TT
  • Weight 0.32 oz
PROS

Purified alumina powder insulator

Dual platinum construction

CONS

Single Plug

11mm Electrode

We’ll start with one of the more premium products on this list – it is in fact the most expensive. However, it is also a multipack, which is something of a rarity these days, when many manufacturers look to sell plugs individually.

So while you are shelling out the most bucks to buy this product compared to some others, you are getting a pack of six. So if you need to replace multiple plugs in one go this could actually be the economy option. Plus, it’s not like these things rot – if you don’t use them all, just tuck them away for the future.

They are well worth saving too, as they are a decent all round plug. Iridium is a premium spark plug material, often giving around 25 percent longer life span compared to cheaper platinum models. The super fine electrode wire also helps to make this a very efficient model.

Key Features
  • Premium Materials
  • Multi-Pack
Specification
  • Brand NGK
  • Model LFR6AIX-11
  • Weight 11.5 oz
PROS

Iridium Tipped

Fine Wire Electrode

Pack of 6

CONS

Expensive

This plug from NKG, quite like the one we discussed above, also uses an innovative design to try to supply the performance of iridium-constructed models at a cheaper price.

While the previous model utilized a double platinum construction, these plugs only have Platinum on the electrode tip. However, they make up with that by employing an incredibly thin (0.6mm!), laser welded tip. That thinness of the electrode will lower the power needs without affecting performance, leading to fast engine starts and improved efficiency.

As a four pack, the initial purchase price is of course higher than a single plug, however divide the price by four and the individual price for each one is about the average price for a decent product.

Key Features
  • Alloy Spark Plug
  • Platinum Tips
  • Thin Electrode Tip
Specification
  • Brand NGK
  • Model 7090-4PK
  • Weight 1 lb
PROS

Platinum Tip

0.6m Electrode Tip

4 Pack of Plugs

CONS

Platinum on tip only

The German firm Bosch is a premier manufacturer of electrical goods, so first of all, you know you are getting a quality product – the name is the guarantee.

What we have here is a very innovative design. The plug tip has been re-designed from the ground up, producing a product that looks very different from the traditional model. What we have here are four yttrium-enhanced electrodes instead of the single electrode and cap system seen on trap>

This provides a plug that delivers excellent performance without having to rely on expensive materials like iridium or platinum. The design is also very straightforward to use – it is literally a plug and play model, with no adjustments required after installation.

This is a great product that will not cost you as much as you might assume. Gut gemacht, Bosch.

Key Features
  • 4x Yttrium Enhanced Ground Electrodes
  • Low Maintenance Design
  • Long Life
Specification
  • Brand Bosch
  • Model 4417
  • Weight 0.32 oz
PROS

Electrodes deliver powerful sparks

Easy to Install – No Adjustments Required

CONS

Single Plug

Relatively Expensive (not that expensive though)

This is a high performance plug with a number of unique features. The first to note is that lovely, 0.6mm width on the tip. Again, that thin tip is going to really enhance engine performance. Add in the fact it’s laser welded platinum and that’s a very good start.

The unique insulator noses are specially designed to improve throttle response too. So this is overall a pretty high spec plug for a relatively low price tag. Therefore, if engine performance is the most important factor to you – but you don’t want to take out a new credit card to buy your plugs – you should definitely take a look at these.

Key Features
  • 0.6mm Tip
  • Platinum Construction
  • Unique Design Insulator Noses
Specification
  • Brand NGK
  • Model NGK7092
  • Weight 1.92 oz
PROS

Tin Tip

Platinum

High Durability

CONS

Single Platinum

Single Plug

With an ACDelco Conventional Spark Plug, you’ll get one reliable and trustworthy part. All ACDelco parts and auto accessories are designed to deliver reliable performance on the road, and they’re made to provide you with the very same level of quality that you’ve gotten from your car’s OE parts.

These spark plugs are no different. Made with high-quality copper cores and standout suppression characteristics, they’ll perform reliability once installed in your engine. Each plug is covered in black onyx coating, which helps reduce corrosion, and a nickel-chrome alloy sheathing that also helps combat potential corrosion. And a ribbed suppressor seal gives the spark plugs better resistance while also preventing flashover and misfires. Though they’re technically aftermarket parts, the spark plugs are manufactured to OEM fit, form, and function standards so you don’t have to sacrifice any normal driving capability.

Key Features
  • Copper core and nickel-alloy sheathing
  • Black onyx exterior coating reduces corrosion
  • Made with a single prong electrode
  • Can be used in vehicles or marine applications
Specification
  • Brand ACDelco
  • Model N/A
  • Weight N/A
PROS

Designed to meet OEM part standards in fit, form, and functionality

Constructed out of corrosion-resistant materials for longevity

Copper cores are highly conductive

CONS

This is a basic spark plug—not one made of more advanced iridium

From the most expensive product on the list to the cheapest – but please don’t write it off and scroll straight past!

True, there is nothing particularly innovative about this plug. Couple that with the copper construction on the electrode and this is a very basic model. However, it is also a nicely put together plug with built in anti corrosion resistance. It is a strong, dependable plug that is built to a high standard for a long working life.

Some engines, especially older ones, specify a copper plug. If your engine spec sheet calls for copper, this is an excellent option for a very reasonable price.

Key Features
  • Copper Tips
  • Built in Corrosion Resistance
  • Solid and Dependable Design
Specification
  • Brand Champion
  • Model 570
  • Weight 0.8 oz
PROS

Cheap

Effective

Great for Older Model Cars

CONS

Copper

If you’re hoping to find spark plugs that are more durable and offer a longer lifespan, the Autolite XP Finewire Iridium Spark Plug is just what you need. These impressive spark plugs are some of the most technologically advanced ever offered by Autolite, and they put iridium at the center of their great performance and improved durability.

Choose these spark plugs, and you’ll discover they’re made great with their iridium-enhanced center electrode, which is more resistant to wear and tear for more longevity. A 0.6 millimeter finewire design paired with proprietary platinum sidewire technology to deliver better ignitability and performance. Together, all of these features and design cues deliver OE form, fit, and function so you can bring your engine back to its original glory. Even more importantly — and impressively — this Autolite spark plug is backed by a five-year limited guarantee so you have a bit of extra reliability.

Key Features
  • Iridium-enhance 0.6 millimeter finewire design
  • V-trimmed platinum sidewire technology helps reduce wear
  • Backed by a five-year limited guarantee
Specification
  • Brand Autolite
  • Model N/A
  • Weight N/A
PROS

Lasts longer thanks to increased durability and resistance to wear and tear

Iridium helps improve ignition and the engine’s ability to spark up

Delivers maximum efficiency regardless of engine type

CONS

Not available for shipping and must be purchased at a Pep Boys store

The E3 Premium DiamondFIRE Electrode Automotive Spark Plug is unlike any other you’ll find. This is a spark plug that uses a special patent and an innovative design to create a better spark and improved combustion. And if you install this spark plug in your vehicle, you can reap a whole lot of benefits.

This particular spark plug is the result of years of combustion research and innovation. It’s made to increase the combustion pressure during an engine’s power stroke, resulting in better power output, improved fuel economy, and fewer emissions. Made with an edge-to-edge electrode, this spark plug offers better efficiency and a faster, more complete burn. You’ll get smoother acceleration and idling with it, thanks to the faster flame burning. Your car’s power output can improve by as much as 6 percent on average — and you can save money on fuel thanks to the impressive results of this spark plug.

Key Features
  • Delivers up to 6 percent more power compared to basic spark plugs
  • Increase power output and fuel efficiency
  • Diamond-shaped for a better combustion spark
Specification
  • Brand E3
  • Model N/A
  • Weight N/A
PROS

Delivers cleaner-burning combustion, which helps you potentially save fuel

Meets OE requirements for a flawless fit and performance in most engines

Simple installation process

CONS

Some users report a loss of power with this product installed

A bit more expensive than basic spark plugs

Basically the exact opposite of the plug above, this product from Autolite is not really designed with premium performance in mind.

What we have instead is a superb everyday plug that is perfectly suited to go into a normal car and perform well in normal, everyday situations. So if you use your car to do doughnuts and hand break turns in parking lots and out run the cops on the freeway – this isn’t the plug for you!

If you commute to work, drive to the mall – in other words use a normal car to do normal things – this is a great plug made with very good materials to a tried and trusted design. It’s a great middle ground between cheaper products of inferior manufacture and materials and the top end, premium plugs and their high prices.

To put it simply – it’s not going to perform miracles, but it’s not going to let you down either.

Key Features
  • Double Platinum
  • Durable Design
Specification
  • Brand Autolite
  • Model APP104
  • Weight 6.4 oz
PROS

Excellent, Everyday Plug

Tried and Tested Design

Low Price

CONS

No Stand Out Features or Materials

The ACDelco Iridium Spark Plug is a step up from the conventional option mentioned earlier on our list. Made with more advanced engineering, more combustible material, and increased strength, this particular iridium spark plug is a part that’ll bring your engine back to its full power and potential.

Made with the latest in spark plug technology, this iridium option is a step up from the old standard. It’s made to be an exact replacement for your vehicle’s original spark plugs, and it should be able to meet the OE fit, form, and function — particularly in GM vehicles, as ACDelco manufactures GM OE parts. The spark plug’s iridium delivers a high melting point along with extra strength, and it’s built with excellent wear resistance so you get better durability. With this spark plug in place, you’ll see better idling, reliable cold starts, and speedy acceleration.

Key Features:
  • Constructed with an iridium center electrode and a copper cored nickel alloy
  • Improves starts, cold starts, and idling
  • Designed with OE fit, form, and function at its center
Specification:
  • Brand: ACDelco
PROS

Iridium is more advanced and offers better stability and reliability

High melting point and high level of strength

Offers great wear resistance for long-term durability

CONS

Best suited for GM vehicles and may not deliver the same performance in non-GE models

Best Spark Plug Buying Guide & FAQ

Spark plugs are small and a little deceptive. Because of their diminutive size, these parts can seem insignificant. But it’s up to your engine’s spark plugs to deliver the combustion you need to get driving.

That’s why choosing a quality spark plug is so important. As your original factory spark plugs wear, you can start to experience engine woes like rough starts, a lack of reliability, and rough idling. Upgrade to a new spark plug, and you’ll discover just how much you’ve been missing in terms of reliability and performance. You’ll even notice better gas mileage, as failing spark plugs can reduce [ Fuel Efficiency by up to 30 percent.]

Hence, why spark plugs are so critically important. Need some help deciding which of the best spark plugs is the best choice for you? Read our buying guide for advice and tips.

spark plugs

How Spark Plugs Work

Well this seems as good a place as any to start – how do Spark Plugs work? Well sir, you just plug them in and they spark. Simple.

Ok, they are a little more complex.

A spark plug is first and foremost an electrical device. It plugs into the cylinder head of a typical engine (*). The cylinder head is flooded with a mixture of air and fuel (gasoline) that the spark plug ignites. This tiny explosion (and that is really what it is!) drives a piston that is attached to a crankshaft that transfers the energy (via a couple more connections) to the wheels of your car, propelling the vehicle.

That’s it! Or at least that is the absolute basic description of the workings of the internal combustion engine. But you should be able to see how important the spark plug is, right?

No spark, no combustion — no engine.

*Diesel engines are a little different, and don’t use spark plugs. Instead, they use Glow Plugs. So if you have a diesel car and have read this guide all the way to this point then… sorry.

Different Types of Spark Plugs

Even though they are relatively simple little things there are a few differences in the various models that you will see available.

spark plugs for cars

Broadly speaking, they are all of the same design — with the exception of the first Bosch plug in the list above, which instead of the typical electrode and cap arrangement had a special 4-point electrode construction. But that was one plug from 10 that was a totally different design.

Instead, the main area where you will notice differences is in the materials used for the electrode and sometimes the cap, which will be constructed with one of three materials:

  • Copper The original, but sadly not the best! Copper spark plugs are the most basic on the market, and as such are the cheapest. However, the have been largely replaced in modern cars by plugs made of platinum or iridium. These two materials just have such better performance and lifespan, many modern engines simply can’t run with copper plugs installed. On the other hand, older engines can often run better with copper, so there is still a place for them.
  • Platinum A great middle ground material, platinum provides a real boost in performance and fuel efficiency compared to copper, but without the premium price tag of iridium plugs. For a real performance boost, look for plugs that use double platinum – both in the electrode and in the cap.
  • Iridium The pinnacle of spark plug tech. Iridium plugs will deliver the best performance, the best fuel efficiency and the longest life span – but also the highest price tags. 

Signs That You Need to Change Your Spark Plugs

Do you know how to spot a failing spark plug? Spark plugs can get forgotten among all of the other kinds of maintenance and repairs a car needs throughout its lifetime. Typically, a copper spark plug will wear out after 10,000 to 20,000 miles on the road. Platinum, meanwhile, can last up to 50,000 or 60,000 miles — and if you have iridium, you’re good until the 100,000-mile mark. 

As your spark plugs face wear and tear, it’s easy to overlook the small, subtle signs of spark plug aging. In order to catch your spark plug’s slow decline over time, you’ll want to look for a few signs in particular. If you spot any of the following changes, it’s time to replace yours.

Rough Starts

Are you having trouble starting your car? It could be worn-out spark plugs. One of the surest signs that you need new spark plugs is a car that’s struggling to start when you push or twist the ignition. If you’re noticing rough starts in the morning, that’s an especially clear red flag for your spark plugs.

Rough Idling

When you’re idling in a driveway, at a red light, or in any other scenario, you should hear a smooth, consistent purr from under your car’s hood. If your car is suddenly idling in a strange, uneven manner — like extra-loud noises, rumbling, or other unfamiliar sounds and vibrations — then your spark plugs might be on their way out.

Engine Misfires

If your engine is starting to stumble every so often (or, even worse, regularly) while you’re starting it up or idling on the road, it’s time to start shopping for spark plugs. Those stumbles are misfires, and they’re a sign that your spark plugs are worse for the wear and unable to help your engine properly combust. 

Slow Acceleration

Have you been hitting the gas to get up to speed and finding your engine is slow to respond? Delayed or slower acceleration is a common problem if your spark plugs are old and reaching the end of their lifespan. Your car should be as responsive as you’re used to if the spark plugs are in good shape.

Worse Fuel Economy

Did you know that your spark plugs play a role in your car’s fuel economy? When this little component is at its best, you’ll see solid fuel efficiency and savings at the gas pump. But as your spark plugs start to degrade and wear out, your fuel economy starts to suffer (and so will your wallet!). If you’re noticing your car is using more fuel, check your spark plugs.

When Are Cold or Hot Spark Plugs Best?

This is a case of opposites attracting. Spark plugs can be designed to have different temperature tips – cold plugs have colder tips and hot plugs have even colder tips. No, wait – hot plugs have hot tips.

When picking the right one, just think opposites. Cold tips are better to use on a very, very hot day. They are also best for high performance engines and/or engines with high RPM. That’s because the tips car cooler, so they operate at a lower temperature allowing the plug to remove excess heat from the engine more efficiently.

Hot plugs are, unsurprisingly, the exact opposite. They are designed to operate with hot tips that means they are always toasty warm even when the air being brought into the engine is cold. This is important, as if the plug is operating in an environment that is too cool, the combustion in the cylinder head won’t be as efficient as it could be. That in turn affects engine performance, and can also lead to deposits building up on the plugs, which shorten their life span.

At the end of the day though you probably don’t need to worry about this too much. The exception would if you are very concerned about getting the maximum engine performance possible, or if you live somewhere very cold (Alaska) or very hot (Florida). In those instances, it could improve engine performance and prolong spark plug life span to select the correct temperature plug.

For most of us though, the types of plugs recommended for our vehicles will take into account the correct temperature, so don’t worry about it too much.

How to Change & Inspect Spark Plugs

Removing spark plugs is relatively straight forward, and this guide should provide everything you need.

Once you’ve got the plugs out, you can tell their condition by how they look, so for example:

  • Look Fine – If they look fine, and the engine is running perfectly, then the plugs are ok to put back into the engine.
  • Fine, with red coating – The engine works fine, the plugs look ok but with a bit of a red coating. That is just leftover additives from cheap gasoline. Clean them off with a cloth and put them back.
  • Worn – If the plug electrode looks worn, i.e. thinner or more brittle than a new plug, it’s time to replace it.

Basically, if the electrode looks ok, the plug is probably ok, because that thin little wire is really the working part of the plug and takes the most punishment.

Top Brands

In your search for the best spark plugs for your vehicle, it’s a smart idea to consider the top brands. Spark plugs come from a number of different brands, but three of those brands stand out from the rest.

NGK

NGK is a company that’s all about spark plugs. This brand specializes in only two areas: ignition components and sensor components. And with a product line that includes all different kinds of spark plugs, NGK offers everything from automotive spark plugs to marine spark plugs and more. Products like our top pick, the NGK 6619 IRIDIUM SPARK PLUGS LFR6AIX, show just how great this brand can be.

Denso

Another brand you’ll see over and over again when you’re shopping for spark plugs is Denso. This company, which is an automotive parts brand based in Japan, was actually once owned by Toyota itself. So, if it’s OEM-level quality you’re looking for, Denso has it within its product line. Check out some of our top Denso picks, like the DENSO 4504 PK20TT PLATINUM TT SPARK PLUG.

Bosch

You probably know the brand Bosch from its power and hand tool product lines — but did you know that this big name also makes automotive parts and components? Bosch makes some high-quality spark plugs that are made with premium materials for easy combustion. Spark plugs like the BOSCH 4417 PLATINUM+4 FGR7DQP SPARK PLUG (SINGLE), are a great example.

Spark Plug Pricing

Great news: replacing your engine’s spark plugs isn’t a costly adventure. In fact, it’s surprisingly budget-friendly. Here’s what you can expect when you go to buy new spark plugs.

    • Under $9: Most spark plugs will barely break the bank. You can find them as cheap as $2 to $9 in an array of materials from copper to platinum to iridium. Even at these low price points, you’re still getting good spark plugs.
    • $10 and up: Spend a little bit more and you’ll be choosing from the top-tier of premium spark plugs. The fanciest and most technologically advanced choices tend to be priced around $10 or more, meaning they’re still quite affordable. 

Benefits of Spark Plugs

Wondering why you’d bother upgrading or changing out your spark plugs? Well, like we mentioned above, letting your spark plugs wear out over tens of thousands of miles — or as much as 100,000 miles — of driving can cause your engine performance to suffer. As your spark plugs see more wear and tear, they become less effective at their primary job. This can leave your engine struggling to start, and you potentially stranded with a non-working engine.

But switching out your old spark plugs in favor of new ones can bring a host of benefits, including:

  • Smoother, faster engine starts.
  • Easy engine starts in cold weather and freezing temperatures.
  • Smoother, more consistent idling.
  • Increased acceleration, especially if you’ve noticed a recent decrease.
  • Improved fuel economy and potential gas savings, if your fuel efficiency has dropped off.
  • Quicker, more powerful combustion inside the engine with every start.

Overall, all of these benefits can improve your engine and vehicle performance. Keeping tabs on your spark plugs and knowing when it’s time to replace them can have plenty of positive effects, making every drive behind the wheel better.

Sources:

  1. Invention of Combustion Engines – BBC
  2. Spark Plugs Affect Fuel Efficiency – Investopedia
  3. How to Change Spark Plugs – The Family Handyman

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