7050 Water in Oil

I recently topped off my 7050 with antifreeze, changed the oil and other fluids.  The next day I checked the oil and to my supprise I find a milky dipstick.  Now when I checked the oil the first day it was fine, but milky the next.  The antifreeze in the radiator had also gone down.  Now I left the water in the rad. at the same level and changed the oil again this time no water in the oil.  Can you tell me if there is a gasket bad somewhere that might cause this?  I dont think its a head gasket because the water dosent enter the oil pan unless the Rad. is completely full.   It runs fine and dosent get over 190 degrees.  with the low coolent.  The only problem is the coolent is to low to heat the cab on cold days.