OP the coolant change schedule for your truck is every 2 years or 24,000 miles! So if you have never had it serviced you might want to get it done. You can do it yourself if you have some place other then the ground to dispose of the old coolant. If doing it yourself I would pull the T-stat add a good radiator flush chemical fallowing the directions on the bottle. Re flush with clear water then reinstall the t-stat and fill with a 50/50 solution coolant and distilled water. Or take it to a good radiator shop near you and have them do it, along with cleaning the radiators exterior of bugs.
Don