I changed my oil, fuel and coolant filters this weekend and was looking at the coolant level in the degas bottle. I noticed that it was lower than the mark that I put on the side of the degas bottle when I installed the coolant filter. The truck drives fine and doesn't smoke a bit. I have an Edge CS Monitor and my EOC & ECT never get more than 7 deg from each other. If you look at my other posts, the truck had the head gaskets, oil cooler, egr valve, ect replaced in 2009 by Ford. (Truck has 139k miles total). I occasionally tow a cattle trailer and a tractor, only about twice a month - other than that, no towing, no heavy foot. What are your thoughts?