Where do you see 6,000? From what I can see the manual says to follow the oil change indicator system.
Scheduled Servicing — Gasoline Engine
Your vehicle is equipped with an automatic oil change indicator system. The oil change indicator system will remind you that it is time to take your vehicle in for scheduled maintenance.
Based on engine operation conditions, the oil change indicator message will illuminate. This means that service is required for your vehicle. Operating conditions such as frequent short-trips, trailer tow, extremely hot or cold ambient temperatures, and E85 fuel usage will influence when the “Oil Change Required” message is displayed. Severe operating conditions can cause the change oil message to illuminate as early as 3,500 miles (5,600 km) since last reset. Have your vehicle serviced as soon as possible, within the next 500 miles (805 km).
Your authorized dealer will reset the oil change indicator message after completing the scheduled oil change.
NOTE: Under no circumstances should oil change intervals exceed 10,000 miles (16,000 km), twelve months or 350 hours of engine run time, whichever comes first. The 350 hours of engine run or idle time is generally only a concern for fleet customers.
Severe Duty All Models
Change Engine Oil at 4,000 miles (6,500 km) or 350 hours of engine run time if the vehicle is operated in a dusty and off-road environment, or is operated predominantly at idle or only very low engine RPM’s. This type of vehicle use is considered Severe Duty.