Spark plugs ignite the fuel-air mixture in your engine. Long-life iridium and platinum plugs last far longer than old copper ones, so the interval depends heavily on the plug type your engine uses.
80k-100k mi
iridium plug life
~30k mi
copper plug life
📊 Quick Comparison
Plug Type
Typical Interval
Cost (set)
Copper
~30k mi
$40-$120
Platinum
60k-100k mi
$80-$200
Iridium
80k-100k+ mi
$120-$300
Intervals by plug type
Standard copper plugs typically last around 30,000 miles. Platinum plugs commonly last 60,000 to 100,000 miles, and iridium plugs often reach 80,000 to 100,000 miles or more.
Always use the plug type and heat range specified for your engine.
Check the manual for the exact interval and plug part number
Replace all plugs as a set, not one at a time
Warning signs of worn plugs
Rough idle, misfires, hard starting, reduced fuel economy, sluggish acceleration, and an illuminated check engine light can all point to worn or fouled spark plugs.
Why timely replacement matters
Worn plugs cause incomplete combustion, which wastes fuel and can damage the catalytic converter through misfires. Fresh plugs restore smooth ignition and efficiency.
Related parts
Ignition coils and spark plug wires (on engines that use them) can wear out too. If you have misfires, have the coils and wires checked along with the plugs.
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❓ FAQ
How long do iridium spark plugs last?
Iridium plugs commonly last 80,000 to 100,000 miles or more, though the exact figure depends on your engine and driving conditions. Check your manual.
What are the symptoms of bad spark plugs?
Rough idle, misfires, hard starting, poor fuel economy, hesitation, and a check engine light are common signs.
Should I replace all plugs at once?
Yes. Replacing them as a set keeps ignition even and avoids repeat labor since they wear at similar rates.
Can worn plugs damage my engine?
Persistent misfires from worn plugs can overheat and damage the catalytic converter, an expensive repair, so do not delay replacement.
Can I change spark plugs myself?
On many engines it is a manageable DIY job, but some require removing intake parts. Proper gap and torque matter, so confirm the procedure first.