If it does this only when cold and overnight, have you thought that you might be losing oil pressure?
Is your gauge a dummy gauge or a real gauge? Does it start off at 3/4 when cold, then settle down a little bit past 1/2 when warm? Or does it stay at the same location the entire time, regardless of engine warmth?
My Jeep is a chick magnet with reverse polarity.
Rampant Pack of Retards group president.
2000 WJ, 4.5l, AX15, 242 D60/14b, 5.5" lift front, 7.5" rear. Ford Expedition rear coils, Ram 350 shocks, JKS, IRO Long Arms, cool Badlands flag thingy.
1987 XJ - Gone but not forgotten