"L" - Frequent Low Speed Operation, Consistent Heavy Traffic Less Than 25 MPH

Frequent low speed operation, consistent heavy traffic less than 25 mph (40 km/h) and/or long rush hour traffic

As required.
- Change engine oil and filter as indicated by message center and perform services listed in the scheduled maintenance chart.

Every 15,000 miles (24,000 km), 6 months, 600 engine hours or as indicated by message center.
- Replace engine- and frame-mounted fuel filters.

Every 15,000 miles (24,000 km) or 600 engine hours.
- Inspect concentration (freeze-point protection) and additive strength (corrosion inhibitor); add engine coolant additive, if required.

Every 60,000 miles (96,000 km).
- Change transfer case fluid (4WD vehicles).

Every 60,000 miles (96,000 km) or 2,400 engine hours.
- Flush and refill engine coolant; do not add engine coolant additive.