Hey guys. I have a 99 F150 4.2 manual that has been trouble free for 135000 miles. About a week ago I had an overheat condition with the heater on only. I quickly replaced the thermostat and it seemed to fix the problem. But, during the procees I noticed oil in the coolant reservoir that was never there before. It is pretty full of oil now. I'm not driving it now but I have no symptoms of a head gasket problem other than the coolant. Oil still is within range on the dipstick, no smoke, no loss of power, no water in the oil. I was just wondering if anyone else has had this problem or heard of it. I love this truck and I'm trying to find out if its worth it to repair it or not.