Ever since I did the PHH a few weaks ago I've been trying to figure out where my coolant is going??? I've probably added about 2 gallons in the past 1000 miles. But no puddles in the parking lot, no smoke on startup or while running, no apparent water in the oil or vice-versa. I've been under the hood & under the truck with a flashlight hot & cold, running and not - nothing. Then today I had to take my daughter to school - only about 4 miles. When I came out I saw a steady dripping. Opened the hood and confirmed that it's coming from the radiator petcock area. Drove to work, made one stop about 10 miles along. No leaking at the stop or when I got to work. So - it only seems to leak when warm? Not hot, not cold. The only thing I can figure is that the window of opportunity is when the radiator has started to develop some pressure, but when it get's hot, whatever is leaking expands to close it off. Strange. I'm going to pull the petcock this weekend and take a closer look - maybe it's cracked or the o-ring is damaged. Any other ideas??