Ford Super Duty (1999-2016) :: 2001 F250 - Antifreeze Leak Parked The Truck In Slightly Forward Downhill Position

I have a 2001 F250 HD gas engine. I have had this truck since 2010. I drive it only occasionally and had not driven it in a few weeks so decided to drive it the other day. I drove about 30 minutes with about half of that on the interstate. It was a fairly hot day mid 80s and I had the AC running. I parked it at a very slight forward downhill position. When I came out after 45 minutes, I saw a puddle of antifreeze in front of the vehicle. When I looked underneath the truck it was primarily dripping from the oil filter canister but also from a couple of other places. I was down about 4 inches in the reservoir. My small truck camper is on the vehicle and I had my coolant container in there.

I topped it off and traveled about 10 minutes on surface streets to my next stop.After about two hours there I came out to the truck to leave and there was not a drop. I then drove 25 minutes home with a little on the interstate running the AC and when I got home not a drop. I got up underneath it and looked all around and couldn't really see an obvious source. My neighbor is a mechanic of sorts and I asked him about it. He had a couple of theories but one involved the heater. He said to crank it up, let it warm up, and turn the heat on and see if I smelled anti-freeze. I did that and there was not a smell at all. He also said something about a cold leak.