Before this big, bad pickup arrived, manufacturers largely used upgraded versions of their light-duty trucks to handle heavy-duty work. The 1999 Super Duty was a separate model line with its own style and hardware underneath.
You can run a conventional oil 5K miles but you should be able to run a synthetic oil 7500 to 10000 miles. Royal Purple API-licensed synthetic engine oils allow motorists to travel as many as 12,000 miles as the recommended oil change interval.
Should you change oil as often as every 3,000 miles then? Unless you want to see your mechanic every two months, a 3,000-mile oil change interval is another extreme. If you check your oil 3,000 miles after your last oil change, chances are it will still be pretty clean. Unless you race your car daily, even mineral oil can last longer than 3,000 miles. Most car manufacturers recommend 3,750 to 10,000-mile oil change intervals.