Ignition System
2. Every 3 years or 45, 000 miles (72, 000 km) - Vehicles operating under arduous conditions: Replace spark plugs. Refer to Spark Plugs .
5. Every 7 years or 105, 000 miles (168, 000 km): Replace spark plugs. Refer to Spark Plugs .
NOTE:
* 4.0 liter V6 engines may have either copper or platinum spark plugs installed.