I have a 2002 4x4 Durango with the 4.7 L V-8. I have 60,000 miles on it and have had this vehicle since it was brand new. I had the vehicle heat up and I replaced the thermostat and added a small amount of coolant that was lost doing this. I pulled off the oil fill cap and found a thick brown substance with water on top off it. so much that I don't think oil could be added. I tried my best to clean it out with 20 Q-tips. I have always had my oil changed at 3,000 miles and went to Mobil 1 last year and run that about 5,000 miles. My coolant was not low and I do not loose engine coolant. When I check the oil level with the dip stick it is at the correct mark and looks like it is almost new, with no foam or water in it. I changed my oil 1/30/2009 and nothing looked out of order about it. I did at that time have a hard time putting oil in. It took a long time to pour the oil in. I cleaned the oil fill tub out then with Q-tips as well. Is this a head gasket problem or because it overheated and the filler tub is high up from the motor and condensates. Any ideas?