4 Types of Spark Plugs (Benefits & Differences)
Updated: Oct 16, 2021
There are 4 types of spark plugs:
Copper spark plugs are used in most OEM cars, iridium, platinum and double-platinum spark plugs are used in the aftermarket industry or in high-performance cars.
When it comes to spark plugs there are some variations. Some are better and others are worse. Iridium and platinum type spark plugs usually last a lot longer than copper ones.
Table of Contents:
Copper Spark Plug
The copper spark plug is the most common and least expensive kind of spark plug available.
While nearly all plugs include a copper core, the common spark plug is often referred to as a copper spark plug, usually they have a nickel-alloy exterior fused to the copper-core.
Copper spark plugs are more powerful and operate cooler. They are often used as factory equipment in most engines.
They are often used in pre-1980s cars with distributor-based ignition systems.
The nickel-alloy material used in the copper spark plug is not as durable as other metals, wearing out more quickly, increasing how often you need to replace the spark plugs.
This accelerated wear causes the spark plugs to fail and stop functioning as effectively as they did when they were new.
Most copper spark plugs should be replaced between 30,000 and 50,000 miles, oftentimes they need to be replaced sooner, even as early as 20,000 miles.
Cheapest type of spark plug
Works in almost any car as they're commonly used in OEM engines
Wears out much faster, needing to be replaced very often, even as early as 20,000 miles
The copper type of spark plug is great for most OEM vehicles, but for high-performance vehicles you may wish to look at iridium, platinum or double-platinum type spark plugs.
Platinum Spark Plug
Platinum is a considerably harder metal with a higher melting point than nickel alloy.
Because platinum is tougher, it retains its sharp edge for far longer than a copper spark plug, around 60,000 to 120,000 miles, sometimes even longer.
Platinum spark plugs have a significant benefit in terms of longevity, they fall short of iridium though.
Another benefit of platinum spark plugs is that they run a bit hotter, which helps to burn carbon and other deposits off of the spark plug, helping improve performance and longevity.
Platinum can also withstand higher temperatures than copper type spark plugs, making use of platinum plugs great for high-performance vehicles.
Stronger than copper type plugs
Has a higher melting point
Burns off deposits on the spark plug
More expensive than copper spark plugs
Platinum spark plugs are great for usage in high-performance vehicles.
Double-Platinum Spark Plugs
The normal platinum spark plug is similar to a copper spark plug in that it has a platinum disc welded to the centre electrode.
Whereas a double platinum spark plug has a platinum disc on both the centre and side electrodes.
This increases the strength of the spark plug further, also helping to burn off deposits.
Further increased strength
Improves deposit removal even more
Costs more than platinum and copper type spark plugs, on par with iridium type plugs
Double platinum may be good for use in high-performance vehicles.
Iridium Spark Plug
Iridium is claimed to be 6x tougher and 8x stronger than platinum, with a melting point 700° higher.
These spark plugs feature smaller electrodes but have excellent strength. This type of spark plug may last up to 20-30% longer than similar platinum spark plugs due to their strength.
Iridium spark plugs include a thin wire centre electrode that is intended to transmit electrical energy more efficiently and improve firing efficiency.
This type of spark plug is more expensive than copper. Iridium spark plugs are usually the most costly, ranging from $15-40 or £10-30 per plug.
Last the longest, 20-30% longer than even platinum spark plugs
Highest strength of all the plugs
Most costly type of spark plug
Iridium is the longest lasting and strongest type of spark plug, great for very high-performance vehicles running high horsepower and high boost pressure.
Which Spark Plug Is Best?
Check your owners manual for the appropriate spark plugs for your particular car.
If your vehicle is designed to run on a specific type of spark plug, downgrading to another type of plug may negatively affect performance.
For example; downgrading from iridium spark plugs to copper plugs can cause issues.
However, upgrading your spark plug from a copper or platinum plug to a double-platinum or iridium spark plug may have a positive effect.