Why is antifreeze in my oil pan?

I have a 97 Ford F150 and it has sat for about 16 months. It is time to get it back out so I changed the oil and found antifreeze in the pan. Before I charge this up and start it could this be nothing or ultimately bad? What to do?Why is antifreeze in my oil pan?
Sounds like a leaky head gasket or cracked head. Remove and inspect your spark plugs. If you find one that is really gooped up then the coolent is leaking into that cylinder. With the spark plugs removed roll the engine over (preferably by hand ) and see if coolent comes out of any the cylinders.Don't charge it up and attemp to start it until you make certain that your cylinders are clear of coolent that may be accumulated there. You can also pressurize the cooling system and see if any coolent leaks into the cylinders.Why is antifreeze in my oil pan?
There could be a couple of things i would check. First thing would be is the Head gasket Dry and cracked , and that is letting water in the Oil passage. or the last time you drove it did it overheat and crack the head.
either you were drunk the last time you put coolant in or your head gasket is blown.
its not good, you could have a crack in the block.