im kinda having the same problem with my 94 civic ex....pulled out the factory motor due to bottom end knock....replaced it with the same d16z6 motor but with only 80k miles....since its been done for only 2 weeks ive been trying to trace this oil leak that im having....its not coming from the valve cover, distributer cap, dizzy or vtec solenoid....im really just hoping that its the oil filter seal because im not sure if the mechanic changed it out or not because the dummy didnt tighten down my oil plug on the pan....i dont think its coming from the oil pan either....when im under the car you can see where the oil is dripping a little from around the tranny where it bolts up to the motor....im not sure if theres a rear main seal or not....will someone get back with me and let me know what it could be before i start paying out alot of money and let me know what i should look for....i did clean the motor up but it started dripping oil again and its hard to trace when im not sure exactly what im looking for.... thanks guys