Guide
Copper vs Platinum vs Iridium vs Ruthenium
The electrode metal is what separates a $3 plug from a $12 one. It drives how long the plug lasts and how sharp its spark stays. Here's the ladder.
The tiers, cheapest to premium
| Tier | Typical life | Notes |
|---|---|---|
| Copper / nickel | 20–30k mi | Best raw conductivity, softest metal, shortest life. Great for some older/high-performance engines. |
| Single platinum | ~60k mi | Harder than copper; holds its gap longer. |
| Double platinum | ~100k mi | Platinum on both electrodes; good for waste-spark ignition. |
| Iridium | ~100k mi | Very hard, very high melting point; ultra-fine center wire for a strong, focused spark. |
| Ruthenium | 100k+ mi | Newest tier; durability in the iridium class with strong performance under load. |
The core trade-off
Harder metal → a finer electrode can be used → a more concentrated, efficient spark → and it erodes slower, so it lasts longer. That's why iridium and ruthenium cost more and go further.
Which should you buy?
If your engine came with iridium, use iridium — don't downgrade to copper just to save a few dollars, as the coil and gap were designed around the finer electrode. If it came with copper, you can often step up to a longer-life equivalent as long as the heat range and fit match.
Find the correct tier for your engine with the vehicle finder, or compare a specific plug's equivalents across tiers in the cross-reference tool.