I'm like an oil leak expert, having spilled more oil from my motors than the exxon valdez spilled in Alaska. All above advice is good. Check the oil sending unit in the back by the distributor Check the valve covers, the intake could do it. the rubber seal that runs across the back of the engine from head to head under the intake. The distributor has a round gasket in between it and the engine. It could be the rear main seal. I did one in my 6.2 in the Jimmy...........patience is definately a virtue needed for that one.......the oil pan is another place...the dipstick tube area where it goes in the block also....the place where the mechanical fuel pump bolts. They do sell stuff that you add to the oil that turns the oil orange, then you can tell where the leak is coming from. Pepboys has will add it and find the leak for 40 dollars by me....I do not know what the orange stuff is called. Also if you add oil stopleak be forewarned that the stuff swells the seals all over the motor, then as time goes on the seals go back to the original size.. I have heard of some problems adding such stuff because it forces the seals out in other places.......good luck!.....leaking seals are a pain in the Axx.......js