The Complete Spark Plug Guide
Spark plugs ignite your air-fuel mixture thousands of times per minute. When they wear out, you get worse fuel economy, rough idle, and reduced power. Here's everything you need to know.
Types of Spark Plugs
| Type | Life | Cost | Best For |
|---|---|---|---|
| Copper | 20–30k miles | $2–5 | Older vehicles, performance builds |
| Single Platinum | 60k miles | $8–15 | Most modern OEM replacements |
| Double Platinum | 80k miles | $10–18 | High-mileage applications |
| Iridium | 100k miles | $10–25 | Modern engines, best performance |
Signs You Need New Plugs
- Rough idle or misfires
- Hard starting
- Reduced fuel economy
- Check engine light (P0300–P0308)
- Sluggish acceleration
Gapping
Always check the gap before installing. Mis-gapped plugs cause misfires. Correct gap is usually 0.040"–0.060" (check your service manual).
Our Top Picks
- **Best overall:** NGK Iridium IX — bulletproof reliability
- **OEM match:** Denso Iridium — factory spec for Honda, Toyota, Subaru
- **Budget option:** NGK V-Power copper — great for older vehicles
Use the vehicle fitment selector to find the right plugs for your exact engine.
