When Should You Replace Your Spark Plugs?
There's no single answer — it depends on what the plug is made of. The electrode metal is the biggest factor in how long a plug survives.
Typical replacement intervals
| Plug type | Typical life |
|---|---|
| Copper / nickel | 20,000–30,000 mi |
| Single platinum | ~60,000 mi |
| Double platinum | ~100,000 mi |
| Iridium | ~100,000 mi |
| Ruthenium | ~100,000+ mi |
These are general figures. Always defer to your owner's manual for your specific engine — forced-induction and some performance engines shorten the interval.
Why metal decides lifespan
Every spark erodes a tiny amount of metal off the electrode. Harder, higher-melting-point metals like iridium and platinum erode far more slowly than soft copper, so they hold their gap — and their spark quality — for far longer. That's the whole reason premium plugs cost more. We break the trade-offs down in the copper vs platinum vs iridium guide.
Can you switch to a longer-life plug?
Usually yes — as long as the replacement matches the physical fit (thread size, reach, seat type) and the correct heat range for your engine. That's exactly what a cross-reference checks. Enter your current plug in the cross-reference tool to see equivalents across tiers and brands.