What is the difference between copper and iridium spark plugs – Jalopnik

The automotive world has evolved to such an extent that engines require spark plugs of a specific type. Using the wrong kind can lead to misfires and inefficiency, especially since spark plugs also come in hot and cold varieties. Spark plugs are typically named for the type of metal on their center electrodes, and spark plugs with nice-sounding metals like ruthenium tend to be more expensive but have a longer lifespan.

The most common and basic type is the copper plug. It has a copper core electrode with a nickel alloy outer housing for improved durability. Copper plugs are widely available at auto parts stores, which is no surprise since they are the most affordable, typically costing $3 to $8 each. In addition to the price, copper plugs have a few more advantages. They tend to run cooler than other spark plugs, making them ideal for older vehicles with distributor-based ignition systems and turbocharged engines with higher compression ratios.

It all sounds well and good, but there’s a reason why spark plug technology has evolved toward harder, more durable metals like platinum or iridium. Copper plugs are great when new, but they don’t last very long as some cars need new plugs every 20,000 to 30,000 miles. Copper is a soft metal, so it can melt and wear out more quickly if it is constantly exposed to intense heat and pressure in the cylinder head. And when it starts to deteriorate, the spark plugs can easily become contaminated with harmful deposits, causing misfires or a difficult engine to start.

Iridium is about eight times stronger and six times harder than platinum or copper. That’s why iridium plugs last longer than most; some can last up to 100,000 miles before they even start to wear out. That’s about five times the life of a comparable copper spark plug, but you’ll have to pay for this privilege.

Iridium may be the adamantium of spark plug metals, but it is a rare metal that makes up only 0.001 parts per million of the Earth’s crust, making it more expensive to produce. Most iridium plugs cost $10 to $25 each, more than three times the price of a copper plug. The cost is somewhat negligible if your car has a V6 or four-cylinder engine, but the cost can increase significantly for modern Hemi V8 engines with 16 spark plugs.

The good news is that not all engines require iridium plugs, so it’s best to check your car’s owner’s manual. Depending on the make and model of your ride, upgrading to copper iridium plugs can help the engine use less fuel and give it more oomph. However, engines that require iridium plugs may persistently misfire, sputter, idle rough, or run with a general sense of lethargy when forced to work with copper plugs.