Most spark plugs should be changed based on their material and your vehicle manufacturer's recommendations, generally ranging from every 20,000 to 100,000 miles. Conventional copper spark plugs typically require replacement every 20,000 to 30,000 miles, platinum plugs can last up to 60,000 miles, and iridium plugs often last up to 100,000 miles or more. Some cars, especially newer models with high-quality plugs, may recommend intervals closer to 80,000 or even 120,000 miles, but always verify in your owner's manual for the exact schedule for your vehicle.

Key Signs to Replace

• Engine misfires or rough idling
• Reduced fuel economy or performance
• Difficulty starting the engine
• Noticeable decline in acceleration

Special Considerations

• Driving in frequent stop-and-go traffic, towing, or using poor quality fuel may require more frequent changes.

• Even long-life plugs should be inspected regularly to prevent issues like seizing in the cylinder head.

Summary Table

Plug Type| Typical Replacement Interval
---|---
Copper| 20,000 – 30,000 miles15
Platinum| Up to 60,000 miles15
Iridium| Up to 100,000 miles157
Some OEM/Modern| Up to 120,000 miles38

Always default to your car's maintenance manual if in doubt, as manufacturer guidance is tailored to your engine.