What Spark Plugs Do
Spark plugs ignite the air-fuel mixture in your engine's combustion chambers, creating the controlled explosions that power your vehicle. Each spark plug fires thousands of times per minute, enduring extreme temperatures and pressures. Worn or fouled spark plugs cause misfires, poor fuel economy, rough idling, and difficulty starting — problems that worsen over time if not addressed.
Types of Spark Plugs
Copper spark plugs are the most affordable and offer good conductivity but wear fastest (typically 20,000-30,000 km). Platinum spark plugs last longer (60,000-100,000 km) with a platinum-tipped center electrode. Iridium spark plugs offer the longest life (100,000+ km) and finest spark thanks to iridium's extremely high melting point. Double platinum and double iridium plugs are designed for waste-spark ignition systems found in many modern vehicles.
Signs You Need New Spark Plugs
Replace your spark plugs when you notice engine misfires (felt as stumbling or hesitation), rough or uneven idling, difficulty starting especially in cold weather, noticeably reduced fuel economy, sluggish acceleration, or if your check engine light comes on with misfire codes. During regular maintenance, also check your oil filter and engine oil condition.
Spark Plug Replacement Tips
- Always replace spark plugs in complete sets for balanced performance
- Use a torque wrench — over-tightening damages the cylinder head
- Apply anti-seize compound to threads (unless pre-coated by manufacturer)
- Check and set the electrode gap to manufacturer specifications
- Replace on a cold engine to prevent thread damage in aluminum heads
- Inspect old plugs for oil fouling or deposits that may indicate other problems
NGK, Bosch, and Denso Compared
NGK is the world's largest spark plug manufacturer, supplying OEM plugs to most major automakers. Their Iridium IX and Laser Iridium lines offer exceptional longevity and performance. Bosch pioneered many spark plug technologies and their Platinum+4 and Iridium lines are highly regarded. Denso is Toyota's primary supplier and their Iridium TT plugs offer twin-tip technology for improved ignitability. All three brands produce excellent spark plugs that meet OEM standards.
Choosing the Right Spark Plug
Always use the spark plug type and heat range specified by your vehicle manufacturer. The heat range determines how quickly the plug dissipates heat — too hot causes pre-ignition, too cold causes fouling. Upgrading from copper to iridium extends replacement intervals and can improve performance. For turbocharged engines, consult your engine maintenance guide and use plugs rated for higher thermal demands.
Shop quality spark plugs from NGK, Bosch, Denso, and more at Fastparts. We carry the right plugs for every vehicle with competitive pricing and fast delivery.
