The Best Spark Plugs You Should Consider Buying

In order to start your vehicle, in an injector engine for example, while the injector retrieves fuel from the storage and supplies it to the engine block, the spark plug is responsible for providing the sparks that allow the piston to explode vertically in the engine block and start the vehicle. This device technically delivers electric current in the form of sparks from the ignition to ignite the fuel and compressed air mixture. Therefore, it is impossible to start your car without spark plugs.

How much does it cost to replace 4 spark plugs?

A set of 4 spark plugs can cost around $30. Besides the spark plugs, you should consider the cost of the mechanic or if you are going to change them yourself. Doing it yourself can be cheaper if you already have the tools to do it, if not you should also consider the cost of the tools.

How does a spark plug make a spark?

A spark is generated due to the electricity running through the spark plug. This electricity is being generated by the battery connected to the plug. This spark ignites the gasoline and air blend in the combustion chamber.

How to diagnose a bad spark plug?

  1. Remove the plug.
  2. Keep it plugged into the cable.
  3. Ground it on the frame of the vehicle.
  4. Start your vehicle and check for sparks.
  5. Blue sparks mean the spark plug is ok. Yellow sparks or no spark at all means you need to change your spark plug.

The Five Best Spark Plugs

In this section, we will be reviewing the best spark plugs covering all types according to the shared experiences of frequent users of the most prominent brands. Even if the products reviewed here don’t fit your automobile needs, you could use the features explained to tailor your preference in accordance with the instructions on your owners’ manual, of course.

20% OFF!
Denso (4504) PK20TT Platinum TT Spark Plug, (Pack of 1)

Product Description


  • Twin-tip technology with 11 mm platinum center electrode and 11 mm titanium enhanced ground...
  • Improve fuel economy, better acceleration and faster starts than all other single platinum plugs
  • Purified alumina powder insulator provides exceptional dielectric strength and thermal conductivity,...

Denso is one of the prominent suppliers of advanced automotive technology and components for major automobile manufacturers with a clear commitment to making Automotive safer. Safety might not have much to do with the function of spark plugs, but it surely projects the image of the brand as one that cares about its customers. That sense of responsibility was used in the manufacture of this Denso 4504 PK20TT platinum model.

Denso Manufacturing Company actually pioneered the use of platinum for spark plugs, so you’re in perfectly-capable hands with this one.

An exceptional amount of dielectric strength and thermal conductivity for proper functioning is provided by the purified alumina powder insulator content that allows the material to withstand extreme stress.

The twin-tip technology featuring 11mm platinum center electrode and an 11mm ground electrode with titanium enhancement helps spread the flame faster, hence a richer combustion.

Make sure that you at least know what you’re doing if you prefer to DIY the installation rather than use a certified mechanic because Denso does not provide any warranty of parts damaged due to incorrect installation or mistreatment – which is a common case with the threading and voltage gap of most spark plugs during installation.

What We Liked

  • Denso 4504 PK20TT Spark Plug is a best seller and one of the most highly rated, racking over 80% five-star reviews on Amazon.com, certainly one of the best spark plugs to buy.
  • This spark plug model was designed towards improving the fuel economy of your vehicle and giving it a faster start/acceleration than other single platinum plugs.

What We Didn't Like

  • A couple customers note that their spark plug started burning, causing the vehicle to vibrate.
Autolite 5224 Copper Resistor Spark Plug, Pack of 1

Product Description


  • Copper-glass seal bonds insulator, terminal post, and center electrode together to provide a tight...
  • Cold-formed steel shell and precision rolled threads, with one-piece terminal post to add strength
  • Multi-rib insulator reduces danger of "flash-over"
  • Resistor reduces radio frequency interference (RFI) and electrode erosion
  • Full copper core electrode provides better performance in all conditions

Autolite brand has been around for a very long while now and has remained very relevant on the market since its inception in 1911. However, since their first production of spark plugs in 1936 and spark resistor plug in 1948, they make sure to match the requirements of new vehicle inventions. With this 5224 model of Autolite Copper Resistor spark plugs, they still haven’t fallen short of their trend.

This model features a full copper core electrode that improves heat transfer as compared to other models and boosts the overall conditions of the plug itself. The center electrode in this copper core also provides higher thermal conductivity to ensure rich sparks at the first ignition.

Its one-piece terminal post features a high alumina ceramic which in turn provides high dielectric strength as well as a steel shell to make the installation robust. The copper glass seal also binds the insulator to the terminal post center electrode in a gas-tight seal to make sure it delivers the required amount of voltage at the spark gap and subsequently ensure 100 percent leak proof.

Apart from preventing leaks at the voltage gap, the multi-rib insulator also prevents misfires by reducing the “flash-over” probability. The resistor embedded in this copper spark plug regulates the radio frequency such that there is little or no interference (RFI).

There’s also a cold-formed steel shell with precision rolled threads to prevent the threading of both the cylinder block and the spark plug from being damaged – especially when handled by amateurs, or handled under frustration. The overall engineering of the Autolite copper spark plug has a centre and ground electrode made of high nickel alloys.

What We Liked

  • Manufacturer-ensured good fuel usage
  • Quick start delivery
  • Provides smooth acceleration
  • Extended durability for a long life span

What We Didn't Like

  • Some customers reviewed that a bad spark plug was delivered in their package
34% OFF!
ACDelco 41-110 Professional Iridium Spark Plug (Pack of 1)

Product Description


  • Iridium offers excellent engine idle stability and smooth performance
  • Iridium allows for small, efficient electrode designs for reliable cold starting and quick...
  • Iridium fine-wire electrode helps burn away carbon deposits on the tip of the plug as they form
  • One piece suppressor seal helps block radio frequencies that can affect vehicle electronics
  • Suppressor seal meters spark energy for long electrode life and helps prevent combustion leakage

This global leader in vehicular replacement parts can be found in six of the seven continents, in more than a hundred countries. They are able to manage such spread with over 100 years of experience dealing with maintenance and replacement parts of about 37 product lines, including this particular brand of an iridium spark plug.

According to the manufacturers, they believe that investing your repair savings into Original Equipment Materials (OEM) is the best thing you could do for your car – and they’re happy to help by making sure none of their products deviate from the OEM standard.

Iridium remains the hardest material used for spark plugs today as they are very efficient for improved cold starting. This is featured in the ACDelco 41 -110 model along with impressive acceleration characteristics and increased fuel efficiency. With maximum resistance to spark erosion and a chamber environment with combustive corrosion, you won’t need to replace the plug throughout its 12-month or Twelve thousand mile warranty. This benefit is also supported by the reduced demands in the ignition system voltage of this spark plug.

For preventing leaks, the one-piece integral suppressor stops compression leakage by sealing the meters spark plug energy.

With the pieces sold per order, you won’t be having any spark plug problems for a very long while. However, you could check the review section on Amazon before you purchase and find out if this really is the particular iridium set that matches your car’s engine.

What We Liked

  • Consistent, correct gaps of 0.04"
  • Best high ratings of its mileage and longevity performance

What We Didn't Like

  • Some customers note that they do not receive the full amount of spark plugs they're expecting in their order.
Autolite APP104 Double Platinum Spark Plug, Pack of 1

Product Description


  • Full platinum tips ensure virtually no gap erosion
  • Works to optimize engine performance for a longer life and improved fuel economy
  • Necked-down center electrode fires quicker and cleaner, with less voltage for easier starts and...
  • High nickel alloy side electrode maintains precise gap
  • Full copper core electrode provides better performance in all conditions

This particular Autolite super performance spark plug model features platinum to platinum firing in the preferred technology for DIS engines. With the addition of a high nickel alloy side electrode, gap erosion and misfires are drastically reduced in its performance.

For extended durability and longer plug life, there’s a nickel-plated steel shell that protects the spark plug from corrosion, full platinum tips with both center and side electrodes made of platinum and a platinum alloy pad on the ground electrode. With this as assurance, you can enjoy its use without any setbacks throughout the span of your warranty.

The necked-down center electrode ensures a quicker and cleaner firing, which ultimately optimizes the performance of the engine and improves its fuel economy.

The Autolite customer service highly recommends that you follow the instructions stated in your owner’s manual before changing any of the spark plugs considering how engines vary widely and differ by certain precautionary instructions.

The warranty on the product lasts 12 months or twelve thousand miles as in most brand models.

What We Liked

  • High rate of returning-customers after first purchase
  • 1-year warranty. Along with a fuel pump warranty— valid as long as the error isn't due to mistreatment or incorrect installation

What We Didn't Like

  • A customer-review noted the spark plugs didn't fit their vehicle model. Ensure it'll fit yours before purchase.
Bosch (4509) HGR9LQI0 9 Platinum IR Fusion Spark Plug, (Pack of 1)

Product Description


  • Fused iridium and platinum center electrode, sintered into an extended insulator nose results in...
  • Revolutionary surface air gap firing technology featuring Bosch's unique four ground electrode...
  • Four yttrium enhanced ground electrodes resist spark plug wear and oxidation for exceptional...
  • Factory pre-set gap allows for easy installation that never requires adjustment
  • Fusion's voltage requirement increases less over time versus other iridium plugs for longer reliable...

Bosch brand founded by the German engineer, Robert Bosch GmbH hosts a German multinational engineering and electronics company which according to the 2011 revenues was the largest supplier of automotive components. That kind of achievement isn’t gotten from running multiple ads and forcing products down people’s throats. That kind of turn out rate definitely means that this German brand is on to something with their products.

This particular 4509 model is one of the latest in spark plug technology. As the name implies, it features a fusion of patented Bosch platinum and iridium. This patented fusion is a combination of iridium and platinum centre electrode with an exclusive surface air gap firing technology. This fusion helps produce a longer and more powerful spark at each ignition.

With technology in place, the spark plug gains a longer performance life during which the fuel combustion gains efficiency. Also, considering the strength and durability of the materials used in this fusion, the ignition system’s voltage requirement reduces eventually, compared to regular iridium spark plugs.

What We Liked

  • Provides features that help reduce the stress on the ignition system
  • It has four yttrium-enhanced ground electrodes which were designed to reduce gap wear significantly and even outperform the Original Equipment (OE) iridium plugs

What We Didn't Like

  • Many reviews have noted it does not perform the best with pick up trucks.

Different Types Of Spark Plug

As a careful reminder, the different types explained in this category also differ in features depending on the engine type and the brand model. Therefore, consult reviews online as well as your car’s manual to see your manufacturer’s best preference.

Copper Spark Plugs

Copper spark plugs are the most common on the market today. While the plus itself is composed is solid copper core, the dead center of the electrode is a 2.5mm diameter nickel alloy. They work best for much older vehicle models, from before the ’80s, since they have a low voltage distribution requirement. Unlike this application, most modern vehicles have high energy distributor systems, and both the copper core and the nickel alloy will wear out too quickly.

This still doesn’t prove that you can’t use copper spark plugs in your vehicle. As mentioned earlier, if according to your owner’s manual, your model calls for copper types, then you have no reason whatsoever to use any other type – for the sake of your engine.

Single Platinum Spark Plugs

Platinum can maintain a sharp edge for over 30 times that of a copper spark plug considering the durability difference between nickel alloy and it. They are known to be the best spark plugs for vehicles with electronic distributors in their ignition systems because they run hotter and leave no spark residues after ignition.

While trying out the copper type to save money might sound like an economical option, if your owner’s manual doesn’t say so, you probably shouldn’t. However, as in most cases, vehicles that use single platinum plugs can also use double platinum or even indium type plugs.

Double Platinum Spark Plugs

These are basically ordinary platinum spark plugs with platinum welded to the side electrode and are designed to handle reverse sparks in the waste spark distribution based ignition systems. In these cases, the spark jumps from the center electrode to the side electrode to power the cylinder on the compression stroke, and this is reversed when a spark is needed on the exhaust stroke.

Positioning the electrodes on both sides allow them to handle these kinds of systems. However, while both single platinum and copper spark plugs cannot work in these engines, you could upgrade to a platinum/iridium combination with iridium on the center electrode and platinum on the side.

Iridium Spark Plugs

Research shows that iridium spark plugs last about 25 times the span of platinum spark plugs. However, while iridium is way harder than platinum, they are also way more expensive and have a reduced diameter of 0.4mm for the center electrode.

Considering the diameter of the electrode, the colder side of the plug in some cases quenches the spark ignited. To combat this, different manufacturers have provided different solutions from which you can choose.

In some cases, the manufacturers add a “U” or “V” shaped channel on the receiving end of the spark plug which allows the Flame to grow quickly and drop into the cylinder. In other products, the manufacturers reduce the flame’s contact with the colder side electrode portion by splitting the ends of the side electrode while it shoots the flame down into the cylinder.

Depending on your preference, you could choose from either of the two designs, as they are equally efficient.

Best Spark Plugs

Having reviewed some of the best spark plug products in every category in the guide above, be reminded that you need to be sure that the information correlates with the requirements in your owner’s manual before purchasing or proceeding to do an easy DIY install.

Also, for extra confidence during installation, you could have a mechanic show you how it’s done first, before going on to do it by yourself. This way, you would be wary of the sensitive areas underneath your hood, and then reduce the chances of tampering with the engine itself.

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