The estimated mileage of iridium spark plugs – depending on the thickness of the central electrode and the construction of the ground electrode – ranges from 60,000 km up to 120,000 km in the case of DENSO Super Ignition Spark Plugs, which feature a protruding ground electrode, like DENSO's Twin Tip (TT) Spark Plugs.
Lifespan of iridium spark plugs
Not all iridium spark plugs are the long-life type, there are also some that have the same lifespan as a normal spark plug: 20,000 km (light automobiles: 10,000 km, motorcycles: 5,000 km).
Ordinary copper and nickel spark plugs should be changed every 30,000 to 50,000 miles, unless otherwise suggested by the spark plug manufacturer. Platinum and iridium spark plugs tend to last longer than standard copper and nickel spark plugs. Expect to change them every 60,000 to 150,000 miles unless otherwise noted.
NGK gives them a life expectancy of 40-50k miles. But they have to temper their projections as driving conditions and motor modifications differ. Typically we have found you can expect 60,000 to 80,000 miles on an unaltered motor. NGK Laser Iridium Spark Plugs have iridium center and a platinum ground electrodes.
Most spark plugs have a factory service interval of 100,000 miles, though some may be as much as 120,000 miles. Long-life platinum and iridium spark plugs will typically last up to 100,000 miles or longer provided the engine isn't using oil or doesn't spend a lot of time idling.
If the tip is worn down, the spark plug needs replacing. If wear is minimal, cleaning the spark plug will restore performance.
Iridium Spark Plugs – Service Life
Denso Iridium spark plugs use a much thinner electrode than even the NGK. Given how long the NGK electrodes last you could argue the NGK are over engineered and reducing their diameter would have no effect on their service life.
Iridium spark plugs are better at starting engines than other types of spark plug because the spark is highly concentrated in the central electrode, and consequentially requires less voltage to operate. This makes ignitions faster and more reliable, and also reduces power consumption.
The only problem with iridium is that it's an expensive spark plug than platinum. So if you're on a budget and yet want an upgrade or some reliability, a platinum spark plug is the answer. It's also one of the best spark plugs recommended if your car has an electronic distributor ignition system.
Platinum is much harder metal than nickel alloy and has a higher melting point. Since platinum is harder, it holds its sharp edge much longer than a conventional spark plug, up to 100,000 miles. Longevity is a key advantage of platinum spark plugs.
Greater engine power from iridium spark plugs
The spark plug manufacturers are unanimous about the fact that iridium spark plugs can considerably improve the engine power. The advantage is crucial when you need to navigate through difficult driving situations or climb steep slopes.
Comparing a normal plug (W20FS-U) with an IRIDIUM POWER (IWF22) on a 2-cycle 50cc engine, fuel consumption improved from 41.74 km/L → 43.69 km/L, an improvement of about 5%.
Standard copper spark plugs last around 20,000 – 30,000 kms. The spark plugs play an important role in your engine, they produce electrical sparks that ignites the mixture of fuel and air in your engine's combustion chambers, causing the pistons to move up and down.
You could expect low-end plugs to last from 15,000 to 30,000kms while high-quality iridium plugs might last up to 180,000kms or more.
Iridium spark plugs are thought to be the most durable and best-performance category of spark plugs globally. They can last up to 120,000 miles.
Its price has surged in recent times due to increased demand from the tech industry. Iridium is one of the rarest elements in the earth's crust. It is believed to have arrived in the same meteor that killed the dinosaurs.
Aftermarket Long Life Iridium Plugs
These plugs are as good as OE iridium plugs and can last for 100,000 miles under normal driving conditions. Some popular ones in this category include Champion Iridium, Denso Iridium TT, and the Autolite Iridium plug.
The copper core does transfer a significant amount of heat. Reeves emphasized that the heat range rating of a copper-core spark plug and an iridium plug will be the same and that it is the tip (overall) length of the center ceramic that determines any plug's actual heat range.
In older vehicles, the ignition system itself is outmoded, and so in most cases the ignition voltage is low. Thus, the merit in using an iridium spark plug that enables stable sparking at a low voltage.
Can I use copper plugs instead of iridium? If your vehicle originally was equipped with iridium spark plugs, it's not advised to downgrade to copper. You'll notice loss of performance and dependability.
So don't rush to replace the spark plug. Pour the toilet cleaner into a cup, put the spark plug in and soak for a few minutes. and the carbon deposits on it will be cleaned.
A spark plug usually lasts about 30,000 miles, but cleaning them and maintaining them periodically lets your engine perform better and increases your plugs' lifespan. If you see rust, carbon, gunk, dust, or any type of buildup during the inspection, it may be time to clean them.
There are several very simple ways to test iridium metal at home including the use of acids and flame tests. A simpler test though involves weighing the metal on a scale against a known weight of gold. If you can then melt the iridium metal, then it will be real however if it remains solid it will be fake.