What Are The Different Types of Spark Plug?

spark plug types

SMALL SIZE MATTERS!! Being so little in size, spark plugs have become a fundamental part of gasoline engines. The caps are responsible for creating ignition for the combustion needed to power up your car. When air/fuel mixture is fully compressed inside the cylinder head, spark plugs produce a bolt of lightning that ignites the combination resulting in an explosion that pushes the piston downward.

Spark plugs are designed with an electrode at the center covered by an insulator with high resistance, good thermal conductivity, and mechanical strength. The shell provides surface protection from corrosion.

Depending upon the metal used to coat the electrode, there are various types of spark socket available in the market. This is where most people get stuck as they’re confused about what kind of plug suits their cars. To make it simple, we recommend sticking with the plug endorsed in the owner’s manual. If you don’t have the manual, here we give you brief ideas about different spark plugs.

Types Of Spark Plugs

Here are list of 4 main spark plug types:

  1. Copper Spark Plugs
  2. Single-Platinum Spark Plugs
  3. Double-Platinum Spark Plugs
  4. Iridium Spark Plugs

1. Copper Spark Plugs

Copper spark plugs are the most basic varieties of spark plugs, also referred to as ‘standard’ or ‘normal’ caps made with a solid copper core. Still, the center end of the electrode is, in fact, a 2.5 mm diameter Nickel alloy, which is the largest diameter for all types of plugs. So, it needs more voltage to operate than others.

Nickel alloy is softer compared to other types of plugs. So, it has a higher wire out possibility due to the sharp firing edge from the box. Copper plugs are cheaper and have a shorter life span.

Despite the disadvantages, copper spark plugs are considered to produce the best spark under critical conditions. Some manufacturers design their engines to keep copper plugs as the original component. But they are not recommended using for modern vehicles with high energy distributor-less ignition systems or Coil-on-plug (COP) ignition systems.

A Note: If your owner’s manual lists copper spark plug as original equipment, don’t go for any up-gradation.

Autolite 3923 Copper Resistor Spark Plug, Pack of 1
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Autolite 3923 Copper Resistor Spark Plug, Pack of 1
  • Copper-glass seal bonds insulator, terminal post, and center electrode together to provide a tight seal that is 100 percent leak-proof
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2. Single-Platinum Spark Plugs

The single-platinum spark plugs are an upgrade of copper spark plugs, welded with a platinum disc to the center electrode’s end. As Platinum is harder than nickel alloy, it holds the sharpness for longer miles under usual driving conditions.

Since the Platinum doesn’t erode as the copper plugs, the gap doesn’t get widened, resulting in improved mileage, reduced misfires on startup. However, the caps are expensive, as Platinum is hard to get in nature.

The single platinum spark plugs run hotter to prevent the plug depositing buildup. The platinum spark plugs are designed for modern vehicles with distributor-based electronic ignition systems.

If your owner’s manual lists this as required equipment, don’t use copper plugs for the shake of saving money.

Single Platinum
1 Reviews
Single Platinum
  • Package Dimensions: 0.94 H x 3.5 L x 1.06 W (inches)
  • Package Weight: 0.1 pounds
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3. Double-Platinum Spark Plugs

Double-platinum spark plugs use platinum plates both in the center electrode and the ground electrode, while single-platinum caps only have platinum plates in the center electrode.

Double platinum plugs spark up twice in the combustion process. The first one is before the combustion, and the later one is during the exhaust stroke. That’s why they are best used in ‘wasted spark’ ignition systems where copper or single-platinum spark plugs don’t fit.

Double-platinum spark plugs have a considerably better lifespan as well as performance than single-platinum spark plugs with a higher price tag.

BOSCH-8116 Double Platinum Spark Plug - Up to 3X Longer Life for Select Chrysler Pacifica, Town & Country, Voyager; Dodge Grand Caravan; Jeep Wrangler; Volkswagen Routan (Pack of 1)
45 Reviews
BOSCH-8116 Double Platinum Spark Plug - Up to 3X Longer Life for Select Chrysler Pacifica, Town & Country, Voyager; Dodge Grand Caravan; Jeep Wrangler; Volkswagen Routan (Pack of 1)
  • Double Platinum firing pin and ground electrode inlay provide 3X longer service life compared to standard copper plugs
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  • 5 year performance satisfaction guarantee
  • Original equipment, pre-gapped replacement delivering optimum fit, form and function for a wide range of vehicles including, but not limited to, the following:

4. Iridium Spark Plugs

Iridium spark plugs come with longer lifespan, more complete combustion to run engines smoothly with a diameter of the center electrode is close to 0.4 mm. The caps require less voltage to operate because of small-sized electrodes.

NGK 6418 Iridium Spark Plugs BKR6EIX ---6 PCS NEW
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NGK 6418 Iridium Spark Plugs BKR6EIX ---6 PCS NEW
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The ‘fine wire’ centered electrodes feature Iridium spark plugs to increase firing efficiency. The caps are mostly used for Coil-on-plug (COP) ignition systems by the manufacturers. The plugs cost you more than others, but it’s worth the price considering the features they offer. If your car manufacturer recommends using Iridium spark plugs, don’t downgrade to other types of plugs.

Also, see the best spark plugs if you are using a Nissan Altima.

Based on the operating temperature, spark plugs are termed as ‘hot’ or ‘cold’ spark plugs. Hot caps have long insulator tips that are more exposed to heat in the combustion chamber. They come with a rich fuel-air mixture to keep the spark plug tip from becoming fouled.

Cold spark plugs, on the other hand, include small insulator tip to remove heat pretty quickly. If the caps you are using get too hot, they cause ‘pre-heating’ to the engine resulting pre-ignition. In this circumstance, you may switch to colder spark plugs. Your car needs Cold spark plugs, especially when you modify the engine for better performance, such as installing superchargers, increasing the compression ratio.


Spark plugs may seem small in size, but they need to be taken proper inspection. Change the plugs when timely to keep the engine performance on top. But stick with the type of the spark plugs recommended by the manufacturer as your engine is designed to work with that.

You absolutely may not want to face any difficulty while driving in the middle of the highway for the sake of faulty spark plugs.