I've only driven my 2500 approx 3300 miles since it's last oil change in May, '01. Trips were not short,generally minimum of 30 or more miles, just didn't drive it frequently, sat in the garage alot. Do I need to change the oil before going on a 1400 mile vacation(no towing involved)?I figure change the oil every 5000 miles, but thought I'd ask since it's got 13 months in the truck. Thanks for your input. SWW