Copper vs Platinum vs Iridium Spark Plugs: Which Should You Buy?

Walk into any auto parts store and you'll find spark plugs at wildly different price points — from $2 copper plugs to $15 iridium plugs. Understanding the difference helps you make the right choice for your vehicle and budget.

Copper Spark Plugs

Copper plugs have been the standard for decades. They have a larger center electrode (2.5mm), good conductivity, and the lowest upfront cost. The tradeoff is service life — copper plugs need replacement every 20,000–30,000 miles.

Best for: Older vehicles with distributor ignitions, high-performance applications where you plan to change plugs frequently, or classic cars.

Platinum Spark Plugs

Platinum plugs use a smaller, harder electrode (around 0.8mm) that wears more slowly than copper. Single platinum plugs last 60,000 miles; double platinum last up to 100,000 miles. They cost more upfront but less over time due to extended intervals.

Best for: Modern vehicles as a mid-tier upgrade, owners who want longer service intervals without paying for iridium.

Iridium Spark Plugs

Iridium is the premium choice. With an ultra-fine 0.4–0.6mm electrode, iridium plugs fire more precisely, require less voltage, and last up to 100,000 miles. They improve throttle response and fuel economy, particularly in high-compression modern engines.

Best for: Modern fuel-injected engines, direct-injection engines, turbocharged engines, and anyone who wants the longest possible service interval.

What Does Your Car Require?

Check your owner's manual. Many modern vehicles specify iridium or platinum. Using copper in an engine designed for iridium shortens spark plug life significantly and may affect performance.

Shop all three types at Texan Supply — free shipping on all orders.