What are the major causes of oil leaks for a 97 plymouth voyager with a 3.0 engine?

Let's see.... valve cover gaskets, cam plugs, distributer o-ring,oil pan( it is sealed with silicone,no gasket ) and front and rear crank seals. If it is up top, you need valve cover gaskets and cam-plugs most likely.. If it is down low, and you have many miles, check between the transmission and engine (rear-main seal) or if it is lower front of engine.. most likely front crank seal