Spark Plugs: Guides by Make & Model

Cheap part, easy to overlook — find your specific model below for the right interval and specification.

Small, Cheap, Easy to Ignore for Too Long

Worn spark plugs rarely announce themselves clearly, which is exactly why so many go well past their recommended interval. Pick your make and model below for the specifics.

Three Main Materials, and a Genuinely Big Difference in Lifespan

Nearly every spark plug has a copper core for conductivity, but what differs — and what determines how long it lasts — is the electrode tip material. Copper (nickel-alloy) plugs are the cheapest and conduct electricity excellently, giving a strong spark even at low voltage, but the relatively soft nickel-alloy tip wears down comparatively quickly — typically good for 20,000–30,000 miles before the widening gap starts demanding more voltage than the ignition system wants to supply. Platinum plugs use a harder tip that resists wear meaningfully better, commonly rated 60,000 miles for single-platinum designs and up to 100,000 for double-platinum. Iridium plugs use one of the hardest metals used in spark plug manufacture, allowing an extremely fine, precise electrode tip that improves combustion efficiency and typically lasts 80,000–120,000 miles while holding its gap far more consistently over that life. A less common fourth type, ruthenium alloy, has emerged specifically for flex-fuel and high-ethanol markets, where standard plug materials wear faster than usual — worth knowing if you regularly run E85 or similar high-ethanol fuel blends.

Always Use What Your Engine Actually Specifies

Fitting a different plug type than your manufacturer specifies isn't simply a lifespan trade-off — it can genuinely cause misfires, engine knock, or premature ignition coil failure, since plug heat range (how effectively the plug tip sheds heat) is engineered to match your specific engine's combustion characteristics. A plug that runs too cold fouls with carbon deposits and misfires; one that runs too hot risks pre-ignition and real engine damage. Don't assume a "better" or more expensive plug than specified is automatically an upgrade — match the exact type and part number your engine calls for, and treat swapping to something different as a genuine engineering decision, not a simple quality upgrade.

Recognising Worn Plugs Before They Cause Real Damage

Watch for rough idle, engine misfires (often felt as a distinct stumble or shudder, sometimes visible as a flashing check engine light), reduced acceleration, harder starting, and a noticeable drop in fuel economy — worn plugs demand more voltage to jump an increasingly wide gap, and eventually the ignition system simply can't deliver a clean, consistent spark. Left unaddressed, prolonged misfiring doesn't just hurt performance: unburned fuel-air mixture passing through to the exhaust can overheat and damage the catalytic converter, turning a cheap plug job ignored for too long into a considerably more expensive repair.

Practical Fitting Notes Worth Knowing

Even pre-gapped plugs can shift slightly in shipping, so checking the gap with a feeler gauge before fitting is worth the extra two minutes regardless of plug type — with one exception: never attempt to adjust or clean an iridium plug's tip with a wire brush or similar tool, since the fine electrode is easily damaged and isn't designed to be manually re-gapped the way a copper plug's more robust tip can be. Torque matters more than many DIYers assume — different electrode materials expand at different rates under heat, so copper plugs generally need less torque than iridium, and manufacturer torque specifications should be followed rather than simply "tightening firmly." Always replace all plugs in an engine as a complete set rather than swapping individual cylinders, since mismatched wear and gap across cylinders causes uneven combustion even if only one plug was actually failing.