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Best Spark Plugs: Iridium vs Platinum vs Copper
Rough idle, hard starts, or worse gas mileage can mean worn spark plugs. Here's how the types compare.
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#1 Best overall: iridium spark plugs
Top pickThe longest-lasting type and used in many modern cars.
Key trade-off: lasts longest, but costs the most.
#2 Good middle choice: platinum plugs
Last longer than copper and cost less than iridium.
Key trade-off: balanced price and life.
#3 For older cars: copper plugs
Cheap and common in older engines.
Key trade-off: lowest price, but need replacing more often.
Before you buy
- Use the plug type your owner's manual recommends.
- Replace all plugs at the same time.
- Many newer cars go 60,000 miles or more between changes, so check your manual.
DIY: How to replace your spark plugs
Safety first: Work on a cold engine. On some engines, the plugs are hard to reach, and a shop may be the better choice.
- Let the engine cool completely. Spark plugs can be very hot.
- Remove one coil or wire at a time, so you don't mix up the order.
- Unscrew the old plug with a spark plug socket.
- Check the gap on the new plug with a gap tool, if your owner's manual gives a gap size.
- Thread the new plug in by hand first, so it doesn't cross-thread, then tighten it to the amount in your manual.
- Reconnect the coil or wire, then repeat for each plug. Start the engine and listen for a smooth idle.
Ready to do it yourself?