I've had problems with having to refill my coolant reservoir tank a handful of times now after a few days or week. The issue at hand is that once the coolant runs out to a certain point on the tank where you can barely see it right above the hoses, it will remain there and never go any lower. The truck has never ran hot,...always runs right under 200. Its making me think there may be a small crack somewhere in the tank just leaking out enough to make me refill it that slowly. Or if it were a bigger problem, a head gasket...but i really am having a hard time believing thats it since it never runs over a certain temp. and no white smoke/blow-by or anything. Any help or ideas would be much appreciated, would like to have this problem fixed and solved so i can flush all water out and put antifreeze in before winter rolls around in a few months. Thanks.