If the cars keep running, the heat stays in the track and dew is not a problem.
The first oildown last night shut the track down for an hour and it cooled off considerably. The second took 2.5 hours to clean up, from starting line to turnoff, from the wall to the centerline. We figure it was around 3.5 acres of oiled surface - oil was dripping from the wall and the centerline timing reflectors. You could see the oil spurting from the engine as the car went down the track. By the time we left the track, windshield wipers were required to keep the dew off the windshield and I am sure the racing surface would have been damp even if they had been able to finish the oil cleanup.