Just getting back from cross country trip. Im pulling 16000lbs of 5er at 70 mph at temps of up to 115deg. I have an 03 CC DRW GMC with 63k miles. Truck runs fine, trans 190deg up and down hills,engine 205 never more than 215 on the tallest hills. Truck hasn't used a drop of coolant since new just noticed hose 2 days ago. Coolant tank still full no unusual noises, runs fine, oil fine. I guess Ill just replace the cap when I get home I dont know what else it could be.