5 Best Spark Plugs

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Using the best spark plugs is a key aspect of having a proper engine performance without misfires.

Of course there’s plenty more involved but today we’re going to focus on the spark plugs. 

During the last 10 years I’ve changed quite a few plugs and diagnosed plenty of problems related with spark plugs and there’s been a few brands and sparkplug series that have worked brilliantly for me.

Here are my favorite 5 sparkplugs reviewed and then there’s a comprehensive buyer’s guide to help you understand this piece of engineering better and making the right choice.

Spark Plugs Reviews

Comparison Chart

21A23rtmeqL. SL500
NGK # 4363 NGK Laser Platinum Spark Plugs PZFR5F-11 —– 6 PCS NEW
Autolite 104 Copper Resistor Automotive Replacement Spark Plug (1 Pack)
Denso (4504) PK20TT Platinum TT Spark Plug, (Pack of 1)
41vu1ogjsHL. SL500
Denso (5304) IK20 Iridium Power Spark Plug, (Pack of 1)
31fAfUgipmL. SL160
NGK (5464) BKR5EIX-11 Iridium IX Spark Plug, Pack of 1

1. NGK Laser Platinum Spark Plug

21A23rtmeqL. SL500

This platinum electrode plug is laser welded to target quick starts and quick acceleration.

It features a 1.0mm platinum electrode and a pre-calibrated .031″ (0.8mm) gap size.

The NKG  spark plug is a superior anti-fouling plug that delivers consistent performance with each fire.


  • High ignitability and long life
  • Slow wear rate for a stable idle, reduced emissions, fuel efficiency and top-notch antifouling
  • Dual ground electrodes provide a consistent and reliable spark


  • Platinum may not be ideal for older model performance vehicles
  • Higher price point

2. Autolite Iridium XP Spark Plug

The Autolite Iridium XP spark plug highlights a 0.6mm finewire iridium-enhanced center electrode for quick response and superior ignitability.

This plug is designed to withstand the rigors of performance driving and each plug is precisely set for the perfect gap and performance

It comes with an incorporated motor seat gasket and terminal nut for easy installation.


  • Autolite’s superior design features, including finewire design and platinum sidewire technology improve ignition and help drivers experience optimal auto performance
  • Guaranteed for seven years
  • OE-equivalent design adapts for every engine to ensure the proper fit


  • Gap may not be accurate out of the box
  • Ceramic is a bit thinner than competitor plugs and may crack

3. Denso Platinum TT Spark Plug

This plug is designed to withstand the rigors of performance driving and each plug is precisely set for the perfect gap and performance


  • Very popular and affordable
  • Twin tip technology gives drivers exceptional performance and increased ignitability
  • Designed to withstand extreme stress for a longer functional life


  • May be difficult to thread in certain vehicles
  • May run too hot and cause misfires in some engines

4. Denso Iridium Power Spark Plug

41vu1ogjsHL. SL500

The Denso IK20 Iridium Power spark plug boasts the smallest central electrode on the market: a 0.4 mm iridium power core.

This plug delivers incredible firing potential for faster flame growth and reduced heat loss.

Manufactured with DENSO’s custom 360-degree laser welding process, this spark plug features a quality bond and unbeatable structural integrity.


  • Super narrow central electrode improves firing time and engine performance
  • Quality construction ensures plug longevity
  • U-Groove technology allows ground electrode to achieve increased ignitability an minimizes voltage required


  • May not fit all advertised vehicles well
  • May reduce fuel efficiency after insulation or over a period of time

5. NGK Iridium IX Spark Plug

31fAfUgipmL. SL500

This plug features a fine 0.6mm laser welded Iridium tip for consistent spark and high durability.

It is designed for the performance car and can deliver superior ignitability and improved throttle reaction.

The Iridium-alloy can withstand heat and electrical wear for an extended plug life.


  • Trivalent Metal Plating resists corrosion and seizing
  • Long insulator nose provides anti-fouling and corrugated ribs halt flashover
  • May reduce misfires


  • May negatively impact vehicle’s fuel efficiency
  • Iridium may not be the best fit for every engine

Tools for Changing Spark Plugs

Regardless of the type, spark plugs will deteriorate over time and need gear4wheels1-20nt. It may take around one hour to replace spark plugs for four-cylinder engines, but doing so will save you paying labor fees.

Under normal circumstances, changing bad spark plugs is a simple task that you can complete in your own garage.

Before replacing your spark plugs, it’s essential to have to correct tools at your disposal. 

  • Spark Plug Socket

A spark plug socket is a specialized socket designed for removing and inserting spark plugs safely. It usually comes with a foam rubber insert that helps keep the spark plug tightly and prevents the socket’s interior walls from being damaged.

  • Flexible Ratchet

Spark plugs are not always installed in convenient spots, which can be cumbersome if you’re using a standard socket. You’ll probably need an extension, or better yet, opt for a flexible ratchet.

This tool is extremely useful for making the removal and gear4wheels1-20nt of your plugs easier.

  • Pull Plier

Spark plug boots can sometimes attach themselves to the plugs. If you still pull in this scenario, it may cause damage to the wires.

Worst-case scenario, the wires will be unserviceable after the gear4wheels1-20nt is completed.

A spark plug boot puller plier lets you pull the boot without damaging the wires.

  • Gap Gauge Tool

To achieve the best engine efficiency and optimum performance, the spacing on the spark plugs must be exactly adjusted. The appropriate gap guarantees that the arcing ensues at the proper voltage for igniting the fuel that allows the engine to function.

Having a spark plug gap gauge tool aids in determining the recommended distance with spark plugs. This improves the spark plug’s functionality by ensuring it produces the spark required to ignite the air-fuel mixture that powers the vehicle.

  • Torque Wrench

To minimize engine damage and other issues, you need to torque the newly-installed gear4wheels1-20nt plug properly. Over-tightening could ruin the cylinder head, while a loose plug can fall off after a couple of uses.

A torque wrench is a hand tool designed to tighten the locking components such as nuts and bolts. Ensuring the proper tension is applied will help avoid the issues mentioned above.

Even though this tool is not mandatory for installing spark plugs, many DIY enthusiasts recommend it. If you want to achieve the correct torque level most efficiently, have a torque wrench ready before you start working.

How to Replace Spark Plugs

1. Prepare the vehicle and find the spark plugs

The vehicle has to be in an area where there’s adequate space for tools and freedom of movement. Ensure the engine is not running, steady, and completely cooled down.

Open the hood to check if the engine doesn’t emit heat anymore. If that is the case, look for the negative battery terminal and disconnect it.

Then, locate a series of wires that leads to the engine’s compartment. These are four to eight wires, usually tied in a bundle.

It’s recommended to read the vehicle’s handbook. In most cases, you’ll learn about where the spark plugs are positioned, how many are there, the socket size, and the recommended gap proportions.

2. Label the wires

To minimize mistakes, make sure the wires are labeled. If you mix them up during installation, the engine won’t work. It can result in cylinder misfires and damage to the oxygen sensor.

Labeling the wires or leads is a simple yet effective means to ensure you’ll have no issues connecting them properly.

3. Pull out the old spark plug

Start by removing the spark plug boots individually while checking the labels if they are accurate.

Usually, the boot consists of silicone and is attached to the tip of the wire. Prevent damage while pulling by holding the silicone instead of the wire. You may use a pull plier if you can’t get a good grip.

After the boots are disconnected, use your spark plug socket to remove the old unit. It usually features a magnetic base that keeps the spark plug stable during installation or removal.

Have the flexible ratchet ready in case you’re having trouble with the location of the spark plug.

4. Inspect the wires

After removing the old spark plug, examine the wires for any damages. While at it, inspect the wire terminals if there is a build-up of debris. You may use a cloth or brush to remove the clutter.

This inspection could be instrumental in making the new spark plug operate properly after installation.

5. Mount the new spark plug

Before putting the new spark plug, it’s recommended to use a gap gauge tool to determine the proper gap distance and adjust based on it.

Once done, use the spark plug socket to mount and tighten the new unit. You’ll know that the installation is correct when you don’t feel any resistance during this process.

If you’re experiencing any difficulties, remove the new spark plug and re-install.

After hand-tightening the spark plug, you may utilize a torque wrench to ensure the torque level is near or matches the manufacturer’s recommendation. Use the labels you made earlier to reconnect the plug boots. You may return the tools to the storage.

6. Test the newly-installed spark plug

If the installation is carried out properly, the vehicle will start normally. However, a misfire may occur if the new unit were fitted out of sequence, overtightened, or loose.

You have to turn off the engine immediately if you observe any indicators of improper installation. Check and redo the installation step if necessary.

You may have to consult a mechanic if you feel that you did everything correct and problems are still there.

Spark Plugs Buyer’s Guide

How do I know which spark plug to buy?

Easy option: Check owner’s manual and just buy those ones. They will surely fit and do the job although they won’t necessarily be the best.

Best option: Check Autozone’s compatibility tool , introduce your car’s year, make model and engine and it will give you a few options from different brands. Note the code and check if any of those spark plugs is the ones I recommend. You can then click on the pic here to check prices and availability on Amazon.com

Electrode Materials

Choosing the correct spark plug for your performance vehicle is essential for getting the most out of your engine. One of the main factors that determines your spark plug function is the electrode material that you choose. There are three primary electrode materials:

  • Copper – Copper is the most widely used electrode material for spark plug design. Copper plugs are very popular for use in performance and modified vehicles because they conduct more efficiently than do iridium and platinum. They have the shortest lifespan of the three conductor materials and generally need to be replaced every 20,000 miles.
  • Iridium – Iridium alloy electrodes feature a high melting point and are very durable, so they last twice as long as copper plugs do. The conductivity of the iridium plug is lower than that of copper and the price point is higher however, the properly calibrated iridium plug can be an ideal option for the performance vehicle.
  • Platinum – Platinum is also a higher quality electrode material, like iridium, and is often preferred for newer cars. Platinum spark plugs are usually not recommended for performance engines, as they have slower conductivity.

Once you have chosen the electrode that works best for your engine mod, you can consider the other factors that influence plug performance: heat and gap setting. You will need to choose the proper settings for your heat and gap setting in order to get your engine to perform at peak levels.

Temperature Grades

Determining your engine’s specific heat range requires referencing your car’s manual and a bit of guess work.

Your fuel will burn within a specific range, and you need to take care to pick spark plugs that do not burn too hot for your engine’s range.

Though hotter plugs will generally lead to faster sparking, going too hot is a danger to your engine and may cause other problems further on down the road.

You also want to take care not to pick a plug too cool for your engine, as it may run too cooly to properly self-clean and will retain unwanted buildup.

Spark plug heat ranges are determined by the length of an individual plug’s insulator tip. The longer the insulator tip, the hotter the plug will run; the shorter, the cooler.

Hot plugs pull heat from the combustion rather slowly and quickly achieve temperature higher than the deposition zone.

Cold spark plugs quickly remove heat from combustion and prohibit advanced ignitions as a result.

Spark plugs manufacturers use thermal values to communicate insulator tip information to consumers.

Typically higher the thermal value, the longer the tip, while lower thermal values signify shorter tips; thus, hot plugs will have a higher thermal value than low ones. Often these numbers are communicated in the part numbers for the plugs and may stand alone or be the last number(s) at the end of an ID string.

Spark Plug Components

The construction of a spark plug goes a long way to determining its overall performance. And while there is great variation among the spark plugs on the market, each plug has the same basic structure, including the following components:

  • Terminal – The terminal is at the top of the spark plug and connects to the ignition system. Terminal constructions varies depending on use, but typically features spark plug wires or eyelet connectors for integration into the system as a whole.
  • Insulator – The insulator is made of a thick hardened ceramic, which is glazed to provide improved resistance for surface spark tracking. It gives support and protection to the central electrode and conducts heat to reduce extended lighting and glowing.
  • Ribs – The ribs are a deeply grooved portion of the spark plug that works to lengthen the distance between the terminal end and grounded end of the plug. The design works to encourage increased electrical insulation and provides protection from energy leakage.
  • Insulator tip – The insulator tip is essential for thermal conduction and is made from hard ceramic. It is designed to withstand heats of up to 650 degrees Celsius.
  • Seals – Spark plug seals stop leakage from the combustion chamber.
  • Metal shell – A spark plug’s metal shell withstands torque associated with tightening the plug and works to draw heat from the insulator and move it through the central electrode to the ground electrode.
  • Central electrode – The central electrode is the hottest part of the spark plug and directs heat from combustion away from the tip with a burst of electrons, thus creating the spark that the engine requires for function. The central electrode also self-cleans the spark plug with intense heat to keep it running smoothly.
  • Ground electrode – Made from nickel steel, the ground electrode is on the side of the metal shell and works to neutralize charges leaving the spark plug to protect the other parts of the engine.


During installation, the spark plug is calibrated to a very specific gap distance for jumping the spark. This distance is determined by individual engine requirements and is somewhere in the range of 0.6-1.8 mm.

The gap must be calibrated precisely in order to deliver proper sparking to your engine.

Too narrow of a gap will lead to an insufficient spark, reducing the engine’s power and efficiency.

Too wide of a gap may lead to misfires, especially at high revs.

When to Replace Spark Plugs

If you see any signs of faulty spark plugs, you should replace them as soon as possible to prevent inconveniences and preserve engine functionality.

After 80,000 miles, spark plugs are usually almost worn out. The gap between each plug will be wider, impacting fuel efficiency and engine performance. To avoid these issues, you must consider replacing spark plugs after exceeding 30,000 miles.

Please keep in mind that a high-performance type of spark plug might require gear4wheels1-20nt earlier than a common plug type since the electrodes could deplete faster.

Final Verdict

Choosing the best spark plugs for your vehicle can help you to experience better engine performance during every drive.

Armed with knowledge about which spark plugs may work best for your application and information from your own car’s manual, you can find the best solution for the performance that you’re looking for.