Best Spark Plugs

(Reviews & Buying Guide)

Best Spark Plugs

NGK Laser Iridium spark plugs are a technological solution of the highest quality. It is one of the best spark plugs available right now. The use of iridium not only improves performance but also double the lifespan of conventional nickel spark plugs.

It has an Iridium alloy tip on the middle electrode by laser-welding using a special technology. The Ultra-thin electrode (0.6 mm) allows to significantly reduce the ignition voltage and improve the propagation of the fire front in the combustion chamber. Thanks to the central electrode’s unique shape, carbon deposits are burned off the insulator’s edge, maintaining the insulating properties and preventing faulty ignition.

It offers the best performance, durability, and fuel economy. These spark plugs have a longer life span than copper or platinum spark plugs because of its iridium construction. 

Key features:

  • Premium material
  • Long-lasting


Denso spark plugs are one of the highly appreciated and best spark plugs in the market. It has Dual Tip Technology, which contains 11mm Platinum Centre Electrode and 11mm Titanium Enhanced Ground Electrode It offers excellent Fuel Economy, better faster acceleration, and engine starts than all other single platinum plugs Purified alumina powder insulator provides exceptional dielectric strength and thermal conductivity, allowing the material to withstand extreme stress. The double tip design allows for a faster flame spread for complete combustion.

DENSO pioneered the use of platinum in the manufacture of spark plugs. To maximize longevity and improve the durability of the spark plug, DENSO applied platinum to the center and ground electrodes. Platinum offers superior resistance to erosion and corrosion, allowing DENSO to create a spark plug capable of consistent performance.

This spark plug offers dual platinum tip and electrode construction. It has a thick electrode tip, which increases its life span. Purified Alumina powder is used in insulation to increase its life. It provides exceptional dielectric strength and thermal conductivity, allowing the material to withstand extreme stress by decreasing the thermal conductivity during operation.

Key features:

  • Twin platinum tips
  • Excellent insulation


These plugs are also from NGK, which is very similar to the performance of iridium spark plugs but in platinum material. The G-Power line is manufactured at the NGK Spark Plug plant in Japan. They have a single electrode tip but a relatively thin laser-welded tip . It offers better efficiency and quick engine startups due to less power consumption of these electrodes.

NGK’s new line of G-Power plugs specially designed for the aftermarket. Platinum spark plugs of this series are distinguished by increased resources and high reliability of the engine’s ignition and fuel economy. The use of platinum as a material for the G-Power plug’s central electrode makes it extremely thin – only 0.8 mm, which has a positive effect, which remains practically unchanged throughout the entire service life of the G-Power plug – up to 90,000 kilometers of vehicle mileage. In addition, the design of the G-Power plugs reduces the load on the ignition coil. It makes the engine start more reliable, which is especially important at low ambient temperatures.

The all-new G-POWER platinum spark plug is designed to provide the power, efficiency, and quality you expect from NGK spark plugs. It is available in a pack of four, but the net price per plug is very reasonable to be best spark plugs.

Key features:

  • Platinum tips
  • Thin electrode laser-welded tip


Bosch is a leading automotive parts manufacturer, and they offer quality products. The spark plugs are one of them. Bosch 4417 Platinum+4 spark plug has a unique and innovative tip design

It contains four electrodes made of yttrium-enhanced material, making it different from the conventional single tip plugs. It offers excellent performance despite the absence of expensive iridium and platinum materials.

This unique design is simple, and no adjustment is required before installation making it one of the best spark plugs.

Key features:

  • Four yttrium electrodes
  • Simple and low maintenance design


NGK has always been superior in spark plugs, and this G-power spark plug by NGK is one of their best products. This spark plug has a 0.6mm thin tip that increases the performance of the engine. It is a laser welded platinum tip, which is good for performance.

It has a unique insulator nose, which is designed to keep in mind the throttle responses. This spark plug is the right choice for better engine performance with a low price tag.

Key features:

  • 0.6mm tip
  • Platinum construction


Champion Copper Plus is the cheapest spark plug in our review list, and the construction is simple, which is made of the copper electrode. But it has an anti-corrosion resistance feature, which improves its service life along with the optimal performance.

Champion Copper Plus is the best spark plug in the copper category, and for those engines designed for copper plugs, this spark plug is the best choice. The price tag is reasonable with the performance and features it provides.

Key features:

  • Copper tip
  • Built-in corrosion resistance


Bosch Double Iridium Iridium Spark Plugs provide high performance and extended service life. Spark plugs from Bosch are highly flammable.

This spark plug offers the best value for money by providing a high-quality spark plug with a much longer service life. It has an iridium electrode and iridium cap, which gives excellent quality and performance.

It also offers four times more life span as compared to conventional copper plugs. Bosch claims that this spark plug is so good in performance and long-lasting that it can give 7 years of guaranteed performance.

Key features:

  • Double iridium material
  • 7-year performance

What is a Spark Plug?

The spark plug is a crucial component in Otto cycle internal combustion engines, decisively determining their performance and precise operation. The car spark plug consists of a small device whose task is to cause the ignition of the fuel inside each cylinder of any internal combustion engine, as long as it is not a diesel engine, an engine that works differently from the gasoline engine and does not need spark plugs.

Each spark plug has the following components:

Terminal: This is the upper part and is generally characterized by a small threaded adapter, whose task is to connect with the pipette.

Ceramic body: consists of the coating and divided into three elements: the body, the ribs, and the insulator. The main task of the ceramic body is to isolate the electric discharge by increasing the resistance. The insulator defines the thermal degree of the spark plug by its dimensions; it runs through the entire spark plug inside the ceramic body and reaches a few millimeters from the electrode inside the cylinder.

The metal body: this is the lower terminal and generates the spark inside the combustion chamber: it consists of the threaded part, the hexagon (essential for screwing the spark plug to the cylinder), and the electrodes.

Types of Spark Plug

There are several types of spark plugs. They are divided into three groups according to the method of sparking and the number of electrodes:

· Standard two-electrode

· Improved multi-electrode

· Prechamber.

In the most common products, only two electrodes are used – the central one and the side one. Multi-electrode spark plugs have one center electrode and two to four side electrodes – this improves spark formation and, as a result, engine stability. In addition, multi-electrode plugs provide better carbon removal from the electrodes.

In the prechamber spark plugs, the side electrode has undergone significant changes, taking the shape of a cone; a gap remains between it and the central electrode, in which sparking and primary ignition of the mixture occurs. The gap has the shape of a nozzle, due to which the mixture (plasma) that has ignited here is thrown into the cylinder and ignites the main volume of the fuel-air mixture.

Spark plugs can have two types of electrodes:

  • Standard solid
  • Bimetallic.

Standard electrodes are made from various steel alloys (as a rule – iron-nickel, or alloyed with chromium and some other metals) and do not undergo additional processing. Bimetallic electrodes have a composite structure; they are made of two metals with different characteristics.

There are several types of such electrodes

· Steel with copper core – copper has a higher electrical conductivity, and the steel shell has high strength and heat resistance

· Sputtered or soldered rare earth / noble metals – yttrium, platinum, iridium

· Noble / rare earth alloy and copper core

· Solid iridium electrode of reduced diameter – only the central electrodes have a current design.

How does the spark plug work?

The function of the spark plug is to bring energy to the combustion chamber using a spark between its electrodes to initiate the burning of the air/fuel mixture. The spark plugs work through a particular sensor (pick-up) placed on the stator, the magnet inside the flywheel, which allows sending an impulse when one or more pistons are ready to generate the explosion. This pulse is sent to a subsequent component, called a coil, a device capable of raising the voltage to 50 kV and causing the electrical discharge necessary to carry out ignition.

Spark plugs have electrical, mechanical, chemical, and thermal requirements during their useful life. The best spark plugs must have following characteristics.

Electrical requirements: They have to operate at extremely high voltage: around 50,000 volts, so they must be highly insulated to create and hold that much charge.

Mechanical requirements: As the combustion chamber’s pressure is very high during the explosion of air/fuel mixture, the spark plugs have to be strong enough to hold that pressure.

Chemical requirements: Many chemical reactions occur inside the combustion chamber, and a lot of residue deposits on the spark plug, so their material must withstand that residue and avoid any reaction with them.

Thermal requirements: As the temperature inside the combustion chamber is extremely high and the outside temperature is low, so the spark plugs have a high-temperature difference between both ends. So they have to withstand high thermal stresses during their lifetime.

The spark plug needs a powerful electric discharge to work. This discharge must ignite the fuel at the instant in which the piston compresses it inside the cylinder, thus generating that typical phase of thermal engines called “burst.” In practice, the spark plug is nothing more than a metal piece covered with insulating material and built to be screwed onto the engines’ cylinder head.

How to change spark plugs ?

So, the step-by-step replacement algorithm will be as follows:

1. Remove the engine’s protective cover and other items if they restrict access to the spark plugs.

2. Using a compressor or brush, remove the dirt around the spark plug so that it does not go well into the spark plug in the future (you can blow the dust entirely with your mouth).

3. Grasp the wire cap as close to the engine as possible and gently pull it toward you to remove the terminal from the spark plug. Do not shake so as not to damage the cap or wire.

4. Take the prepared socket wrench with an extension and a spark plug head and use it to unscrew the old spark plug from its seat. It is better to twist and change the spark plugs one at a time. If not, mark the wire connection sequence.

5. Check the condition of the spark plug wire (lighting a flashlight if possible). If necessary, clean it and use dielectric grease. And it is advisable to apply a silicone dielectric compound to the connection terminal so that it will be easier to disconnect from the spark plug in the future.

6. Also, check the cables and terminals. You can use a wire brush, rags, or a compressor with compressed air to clean them. If the insulation or wire terminals show significant wear, it is best to replace them. The insulation resistance value can be checked with an ohmmeter (multimeter). Its value should not be less than 0.5 megaohms.

7. Screw a new spark plug into the socket. In this case, it is advisable to use a dynamometer that indicates the torque. If you don’t have a dynamometer, select the “feel” value. There is no need to “twist” the spark plug, which can damage the wire and stop the heat transfer.

8. Connect the terminal to the spark plug.

9. Install previously removed protective elements, including a protective cover.

Symptoms of failing or bad Spark Plugs

Irregular idling

Typically, in the “idle” speed, the engine develops around 900–1,000 rpm. If the engine’s sound becomes rougher and irregular during idling, or if you feel vibrations, in this case, the diagnosis is that the spark plugs are not doing their job correctly. Better to replace them as soon as possible, to avoid engine trouble.

Startup problems

Low fuel or low battery? Could be. However, if the engine struggles to start, these are not the only causes. A glance at the spark plugs will reveal their bad condition: they may be dirty or have worn contacts. In this case, the spark plug fails to produce the spark necessary for the bursting phase. The possibility that because of this also the battery is drained is far from rare. There is only one remedy: replace the spark plugs (and, if necessary, the battery too) as soon as possible.

The engine “misses.”

If you feel a weird operation of the engine, which in practical terms translates into momentary “jerks” while driving, then the engine loses bumps or misses fire. This may be due to the control unit’s malfunctions or – even here – to the low spark coming from the spark plug. How to fix it? There is only one solution: change the spark plugs (and the environment will also gain).

Too much air to the engine

The combustion process is regulated with extreme precision: the quantity of air introduced must be sufficient to make up the air-petrol mixture that the spark of the spark plug will cause to explode. If the vehicle sucks in more air than it should, the motorist – and the mechanic – notice it all right: the car begins to jerk, the more air is drawn in. Changing the spark plugs is the first remedy to perform.

The engine consumes too much fuel.

Without a visual examination of the body and the electrodes, it is not possible to know if one or more spark plugs are deteriorated or worn. But there is a possible worn out if the stops at the petrol station become more frequent. It means that the engine needs more petrol to run, so consumption increases. Nothing serious: just change the spark plugs.

Spark Plug FAQ’s

How often should we change the spark plugs?

Replacing spark plugs only when they fail is not exactly the right approach. This approach can lead to engine damage. It is important to avoid malfunctioning spark plugs. It is necessary to follow the manufacturer’s recommendations, which regulates the replacement intervals of spark plugs.

It is essential for spark plugs to be well cleaned and functioning, the maintenance of these elements is necessary for the car to function. A periodic check of their condition by a specialized mechanic is required not to risk that they no longer perform their vitally important task. A great tip is always to keep them clean. If you have an older car model, it is recommended to replace the spark plugs every 20,000 km traveled.

Some motorists ignore the task and therefore forget their maintenance, later finding themselves with significant car problems, such as high fuel consumption, irregular operation, and excessive exhaust emissions.

How often the spark plugs change is difficult to say. It is possible only after a visual inspection. Typical signs for installing new spark plugs are:

  • The appearance of carbon deposits and oil stains on the surface of the spark plug
  • cracks and other damage on the insulating part
  • mechanical defects on the contact terminal
  • melted electrodes
  • mechanical malfunctions of the thread

What are the main symptoms of a malfunctioning spark plug?

First, if the starter motor starts when the engine is started but does not ignite, this could indicate that the spark plugs are failing.

The second symptom of a malfunction is if the engine twitches while driving and does not develop maximum speed.

Third, pay attention to fuel consumption and exhaust color. Excessive fuel consumption and black smoke can also be the result of defective spark plugs.

Is it possible to determine the condition of the spark plugs by visual signs?

Yes, if you can unscrew the spark plugs yourself. If this is not possible, contact the service station. With the help of specialists, check the size of the gap between the electrodes and the presence of carbon deposits. The presence of dry black soot on the electrodes and an increased gap between the electrodes indicates the need to replace it.

How to determine if the gap between the electrodes is more than normal?

Each spark plug has a so-called marking, which contains information regarding the size of the gap. The marking may look like this: BPR7ES12. A number indicates the size of the allowable gap at the end of the marking. If there is no figure, then look for product manual. If the clearance is less than normal, it can lead to decreased engine power and increased fuel consumption.

Leave a Comment

Your email address will not be published. Required fields are marked *

Scroll to Top