Spark plugs come in a variety of different metal combinations; the common ones being copper, iridium, and platinum. Copper spark plugs are the most popular of the three and are often viewed as standard.
Many car owners often have a hard time choosing between the three especially when it comes to upgrading to platinum or iridium. The key to knowing which type fits your car is understanding the impact the metal used has on your vehicle and recognising the differences in performance and longevity.
What does a spark plug do?
For combustion of the air and fuel mixture to occur in the combustion chamber, there must be a spark. A spark plug provides precisely that. It is screwed into the engine’s cylinder and ignites a spark when a high amount of voltage is sent through it from the vehicle’s coil pack. A spark plug has two electrodes: the center electrode and a side electrode.
It uses a voltage to generate a visible engine spark when an electrical energy jumps the gap between the plug’s center electrode and the ground electrode. This spark leads to the ignition of the mixture of air & fuel resulting in a small explosion that keeps the pistons moving. The material used to make the electrodes is different, and this determines the spark plug type.
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Types of spark plugs
It’s easy to make the cardinal mistake of thinking spark plugs are all the same since they technically serve one purpose. That’s not the case though. Spark plug options differ based on the metal combinations used to make the electrodes.
The three common spark plug types are:
- Standard copper spark plugs
- Platinum spark plugs (single or double)
- Iridium spark plugs
Spark Plug Comparison Table
|Spark Plug||Central Electrode||Price||Performance||Durability|
Standard copper spark plugs
Standard copper spark plugs have the largest diameter and as you’d expect they are bigger than the other types of spark plugs. The electrodes here are made from the copper core, with the tip covered by a nickel alloy. The nickel alloy cover material is crucial as it protects copper whose melting point is low. However, it’s not particularly durable, and the spark plug still wears down due to the high pressure and heat in the engine cylinder.
Note that almost all spark plugs have a copper core element because it has high electrical conductivity and effective heat dissipation. Standard spark plugs are ideal for older vehicles (rolled out before the ‘80s) with basic engines. Such vehicles don’t have many electrical needs, which makes the sparks plug last longer.
Pros of copper spark plugs
- They tend to be cheaper compared to the rest, and they rarely cause problems when replaced regularly.
- They are regarded as the best performance-wise.
Cons of copper spark plugs
- A large amount of voltage is needed to produce a spark because of their large size.
- Their short life span means they need to be replaced after an average of 20,000 miles.
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Platinum spark plugs
Platinum, like iridium, doesn’t offer the high-quality performance that copper does. Spark plugs that feature platinum are less conductive, but they have better longevity. On average, they need replacement after every 40,000 to 60,000 miles. Their performance is decent, and they handle heat better than standard spark plugs.
The tip here is more durable than the nickel-alloy material used in a standard copper spark plug. They’re available as single platinum spark plug or double platinum spark plug, depending on the platinum tip design used.
Single platinum spark plugs
These plugs are much like copper spark plugs in their design. The only significant difference is that they have a platinum disc welded onto the tip end of the center electrode. They are suited for you if your vehicle use the non-conventional electronic ignition system.
Double platinum spark plugs
Double platinum spark plugs feature a laser welded platinum plate on the center and ground electrodes. The spark crosses the gap between the center and side electrode and then back. These plugs are better than the single platinum spark plugs because they aren’t affected by the surrounding environment. They are a great option if your vehicle has a wasted spark ignition system.
While they are not as efficient as iridium spark plugs, platinum spark plugs cost less, making them the middle-tier option.
Pros of platinum spark plugs
- The platinum component handles high temp conditions better
- They are more durable than standard copper spark plugs.
- They generate a lot of heat which reduces debris build-up and fouling.
Cons of platinum spark plugs
- They are inefficient in terms of engine performance.
- They are not as durable as iridium spark plugs.
Iridium spark plugs
These plugs address the durability challenge by using a harder and more durable metal in iridium. To put this into context, iridium is about 8× stronger and 6× harder than platinum. These spark plugs feature a small wire center electrode and have complete combustion. Iridium is also an equally good electric conductor, and overall, the plugs are efficient.
They generally need replacement after an average of 50,000 to 100,000 miles. The catch with iridium spark plugs is the price tag. They cost more than the other types and are typically installed in newer vehicle models that use high performance engines. Many automakers have recently started adopting them because of their fine wire center electrode, which translates to high firing efficiency.
Pros of iridium spark plugs
- They last longer than both standard copper plugs and platinum plugs.
- They have less voltage requirements.
Cons of iridium spark plugs
- They are expensive because of the iridium component.
- Since they don’t require regular replacement, they can easily get stuck and give you a hard time when changing.
When dealing with car components, it is important to balance the initial budget and cost of repairs or replacements in the future. This applies to spark plugs as well.
Your owner’s manual is the best reference if you want to know the best spark plugs for your vehicle. As a rule of thumb, it’s not advisable to downgrade to lower quality spark plugs because they’ll likely cause reduced engine performance. So, if the manual specifies an iridium spark plug, don’t swap it for a copper one.