My girlfriends 89 5.0 has had an oil leak for a while, we replaced the rear main which seamed to solve it. However, now, after driving for about 15-20 miles the oil light will come back on and upon checking the oil, the pan is completely empty. The car sat for a day or two after that without putting any new oil in, after that two days the oil was back in the pan. So basically, the oil will not drain back into the pan and is sitting somewhere up in the top of the engine. We just took the valve covers off to replace gaskets and check the drainage holes on the front and back, they ended up being completely clean. We removed the lower intake to see if there was any noticeable clog, and still there’s nothing. Does anyone know what it might be? Any suggestions? The car wasn’t taken care of the best before we got it but we haven’t found any noticeable reason for the oil to not drain back into the pan.