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Review: Best Spark Plug

Spark plugs are a critical component of engine maintenance, yet many drivers remain unaware of this requirement. Old, worn, or dirty spark plugs will decrease your engine's ability to perform, as they will be unable to ignite the fuel/air mixture as efficiently as they should. Having good spark plugs will make your engine run smoother, cleaner, and consume less fuel.

These best spark plugs in 2021 make use of the latest technology and materials, and can achieve both high performance and durability without compromise. While these highest-performing spark plugs may come with a higher price tag, their ability to increase your engine's overall performance will be worth the added cost.

Top Picks for Best Spark Plugs

Denso Iridium Power Spark Plug

One of the main benefits of using iridium in spark plugs is its extremely high melting point at nearly 2500 degrees Celsius. The Denso Iridium Power spark plug takes full advantage of this attribute by using a fine-tipped 0.4 mm diameter electrode in place of the more traditional wide-diameter offerings. A standard electrode of that diameter would more than likely melt after prolonged use, but the Iridium allows for a more precise, controlled spark-to-ignition process.

Combined with Denso's exclusive U-Groove pattern ground electrode, this allows the Iridium Power to handily outperform its competitors. However, this performance comes with a premium price tag. At more than three times the price of a standard spark plug, it's hard to make a case for the average, casual driver. If you are a performance enthusiast or a long-distance commuter, the cleaner burning capability and potential for increased fuel economy with the Denso Iridium Power may be worth looking into.

AC Delco Iridium Spark Plug

Aside from being an excellent overall spark plug, AC Delco Iridium spark plugs are used as original equipment in premium and high-performance products from GM. Thanks to the higher melting point that the iridium electrode offers, this allows a more powerful spark that would wear out standard spark plugs. The powerful spark ensures a thorough ignition of the fuel/air mixture, meaning your engine will run much cleaner and smoother.

The AC Delco Iridium spark plug requires little to no maintenance, though it’s always a good idea to check gap spacing every once in a while if you suspect that the spark plugs are becoming worn. These spark plugs are rated to last 100,000 miles, and will offer substantial performance for the entire duration of their service life.

Bosch Platinum +4 Spark Plug

For the vast majority of drivers on the road today, the Bosch Platinum +4 can be considered the best all-around spark plug. The Platinum +4 achieves its high performance by employing four (as opposed to one) yttrium-enhanced ground electrodes. This creates a powerful, long-duration spark which is better suited to igniting the fuel/air mixture in any engine, high performance or not.

This spark plug requires no gapping or maintenance - you can simply install these in the engine and 'forget' about them until the next time you need a tune-up. The price of the Bosch Platinum +4 falls neatly in between a traditional spark plug and Bosch's own Platinum IR Fusion model, meaning that these performance spark plugs can even be considered relatively affordable.

best extended spark plug

Performance Tool. W80533 Extended Spark Plug

The Extended Spark Plug Socket 3/8in. Drive, 5/8in., Model# W80533 by Performance Tool (Wilmar Corp) is great because of the quality you get for the price. At around $5, this socket is incredibly easy on the wallet. Plus this socket is also deeper than other comparable tools at 5 inches long. This extra length is good if your spark plugs are in a hard to reach place and you don't have an extension bar to use. The final reason I have decided to include this tool on the list is because it has a knurled design. This increases the grip of the socket, which is good to have if you ever get sweaty palms while working.

Buyer's Guide

What is Important to Know About Spark Plugs

One may not know how important spark plugs are to your car, but that does not take anything away from the vital role they play in ensuring that it runs well. They help perform the all- important function of igniting the gasoline in the combustion chamber with the help of just a little bit of electricity. A car engine will literally not move without a spark plug. As time goes on and a car’s fuel efficiency falls, a major reason could be worn out spark plugs.

A bad or ineffective spark plug leads to a misfiring engine which often makes the check-engine light come on. This could lead to higher tailpipe emission as well as impaired fuel economy and reduced power. If not attended to for very long, this could even damage your car’s catalytic converter.

When Do You Need to Change Spark Plugs

Spark plugs last for a really long time and it is years before you need to think about replacing these. Most automobile manufacturers, however, recommend a change every 30000 miles. That being stated, how long a spark plug is going to last depends on the kind of spark plug being used. Copper plugs don’t last as long as spark plugs made out of more durable new-age materials that enhance their lives by as much as four times that of copper ones.

Why Do You Need to Replace Spark Plugs

Spark plugs endure thousands of miles of rough use involving exposure to the most extreme of conditions. The ones made of new-age materials are better able to withstand such conditions and are therefore able to last longer. But the wear and tear is relentless and ultimately, they do get damaged. Among the principal reasons for damage are:

Spark plug deposits

Deposits that form on spark plugs on account of interaction with the air-fuel mixture can pre -ignite the fuel leading to an erratic supply of energy to move the car forward.

An Expanding Gap

Every time a spark plug ignites, it has to traverse a gap to enable the right level of combustion at exactly the right moment. With age, this gap expands making the combustion inefficient.

How Does Replacing a Spark Plug Help?

For starters, the car will start well! Several other advantages accrue on account of replacing a spark plug. Let’s look at what these might be.

Optimal Combustion Every Time

Spark plugs that function properly lead to an efficiently functioning combustion system. You will no longer have to contend with performance issues.

Enhanced Fuel Economy

Spark plugs that work at less than peak efficiency can reduce fuel efficiency by as much as 30%. Needless to say, the new spark plugs will enhance fuel economy and thereby help one save money.

Better Starts

The difference in the manner one is able to start a car fitted with a new spark plug is palpable. You will experience none of the old jerky starts that would hassle you so often.

Fewer Harmful Emissions

Using fully functional spark plugs not only help save fuel but also lead to fewer harmful emissions. With environmental pollution, being such a major concern these days, it sure makes sense to ensure that one has no spark plug issues.

Improved Acceleration

Smoothly functioning spark plugs optimize the combustion process in a car’s engine thereby ensuring the right kind of acceleration. Old and worn-out spark plugs on the other hand make a car’s engine respond slowly and sluggishly, requiring you to increase the pressure on the gas pedal to compensate for the loss in power.

Now that we have established how important spark plugs are for a car let’s look at which ones are premier brands available in the market.


Robert Boshch GmbH, also known as Bosch have been in business since 1886 and have established a name as a legendary German electronics company. They manufacture a vast range of goods encompassing everything from appliances to auto parts. Of the latter, the Bosch 6702 Platinum Spark Plugs are extremely popular.


ACDelco is a General Motors-owned automotive parts brand that manufacturers a diverse range of products including things like air conditioning components and batteries. It is however the most well known for its range of spark plugs including the best known ACDelco 41-993 professional iridium spark plug.


This one is a well known Japanese brand owned by NGK Spark Plug Co., Ltd. which was founded back in 1936. It manufactures a range of products including curing tools, ceramics and so on, but is really famous for its line of spark plugs. The most sought after of these is the 6619 Iridium IX Spark Plug.

How Much Do Spark Plugs Cost?

Spark plugs have a varied range of prices allowing you to choose one that suits your budget and purpose. The principal categories are as under:

Less Than $3

These are the cheapest types of spark plugs and one must be sure of what one is buying as the quality is known to vary quite a bit in this category.

Between $3 and $9

This is the most popular price category on account of the fact these are quite efficient in their performance and last long as well. This truly is the value for money category, in as much as spark plugs are concerned.

$10 and Above

This is the premium category of spark plugs and offers a sturdy build on account of the use of superior materials, cutting edge electrode designs. Quite naturally it offers extraordinarily good performance in terms of efficiency and longevity.


Thus we see that spark plugs are an extremely important auto component whose importance is belied by their size. It makes eminent sense to go in for the best-performing ones if one wants one’s car engine to run smoothly for a very long time. Among the most recommended ones are the NKG 6619 Iridium IX Spark Plugs, the Denso 4504 PK20TT Platinum Spark Plugs, Bosch ZGR6STE2 Copper with Nickel Spark Plug, Bosch X5DC Copper with Nickel Spark Plug, NGK 3403 G-Power Platinum Alloy Spark Plug, NGK 7090 BKR5EGP G-Power Spark Plug, Champion RC12YC Spark PLug, Autolite APP5325-4PK Double Platinum Spark Plug and Bosch 9614 Double Iridium OE Replacement Spark Plug.

If you think that you could go in for spark plug replacement you now know which ones you could consider buying. Getting a new set of spark plugs for your car will breathe new life into the latter and driving will once again be the pleasurable experience that it was always meant to be. Besides, you will save money on account of better fuel economy and cause way less pollution as well.

Bestcovery Staff
Our research team searches out the best of everything so that you can confidently pick the perfect products and services for your needs.
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