NGK manufactures more spark plugs than any other company in the world - and for good reason. Their iridium and platinum plugs set the standard for OEM and aftermarket ignition. Here's how to choose the right plug for your vehicle.

Spark Plug Types: Copper vs Platinum vs Iridium

Copper Core Plugs (Standard)

Traditional spark plugs with a copper core and nickel alloy electrode. Excellent thermal conductivity - runs cooler than precious metal plugs. Good performance but shorter service life (15,000-30,000 miles).

  • Best for: Older vehicles (pre-1990s), performance/racing applications (replaced frequently), vehicles that spec conventional plugs
  • Change interval: 15,000-30,000 miles

Platinum Plugs (Mid-Range)

Platinum tip on the center electrode (single platinum) or both center and ground electrode (double/twin platinum). Significantly longer life than copper.

  • Service life: 60,000 miles (single), 100,000 miles (double)
  • Best for: Modern vehicles specifying platinum plugs, good balance of performance and longevity

Iridium Plugs (Premium)

Iridium is harder and has a higher melting point than platinum - allowing a finer electrode tip (0.6mm vs 1.1mm for platinum) that produces a more focused spark and easier ignition. NGK's iridium plugs consistently outperform in cold-start performance and fuel efficiency testing.

  • Service life: 60,000-100,000 miles
  • Best for: Modern direct injection engines, turbocharged engines, maximum cold-start performance, OEM replacement on vehicles specifying iridium
  • NGK iridium lines: Iridium IX (performance), Laser Iridium (OEM replacement), Ruthenium HX (premium)

NGK Part Number System

NGK part numbers encode the plug's specifications:

  • First letters: Thread configuration and reach (B = 14mm, D = 12mm)
  • Number after letters: Heat range (lower = hotter, higher = colder)
  • Final letter(s): Construction details (R = resistor, IX = iridium, etc.)

Example: BKR6EIX = 14mm thread (B), tapered seat (K), resistor (R), heat range 6, projected tip (E), iridium (IX)

Heat Range: Critical for Performance

Using the wrong heat range causes problems:

  • Too hot (lower number): Pre-ignition, detonation, melted electrodes
  • Too cold (higher number): Fouling, carbon buildup, rough idle, misfire

Always use the heat range specified by your vehicle manufacturer. Only change heat range for modified engines with significantly different combustion temperatures.

How to Install Spark Plugs Correctly

  1. Allow engine to cool completely - never remove plugs from a hot engine
  2. Clean around plug wells before removal - prevents debris from entering cylinders
  3. Apply anti-seize compound on threaded plugs (but not iridium - NGK recommends dry installation on iridium)
  4. Hand-tighten until snug, then torque to spec (typically 13-20 ft-lbs for 14mm plugs)
  5. Never use an impact wrench - stripped threads in aluminum heads are expensive

Shop NGK Spark Plugs

We carry NGK copper, platinum, iridium, and ruthenium spark plugs for all vehicle makes and models.

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