Place a piece of clean cardboard under the engine while it's parked overnight.This will determine if it is engine oil,transmission fluid,brake fluid ,etc.It will also give you an indication of exactly where it's coming from.One place I didn't see mentioned in the above comments is at the front of the engine.You have crank sensors,cam sensors and one other item most people don't know about.The crank pulley,sometimes known as the harmonic balancer will get a "groove" or ring cut into it caused by a hardened crank oil seal.It will actually cut into the neck of the balancer!I don't know if this is the case but if oil is coming from the front lower side of the engine,and YOU HAVE replaced the oil pan gasket,it's a shot.Go to Rock Auto.com and look for a repair sleeve or a new balancer.It will be found under the engine section for your vehicle.

The Positive Crankcase Ventilation valve (pcv) should allow the compression gases that makes it past the piston rings to go back through the intake and back into the cylinders. If the pcv valve screws up the gases end up building pressure in the crankcase, until it blows out gaskets. Replace the valve and make sure the hose is cleaned out

AS mentioned above:

- oil pressure sensor (lots of oil)

- oil cooler gasket (behind the oil filter)

- timing covers (if chains driven)

- bottom drain plug

- oil filter

- every PCV orifice, but little oil will come out at a time

Clean the engine completely to find the leak. I did this and found that oil was seeping up the centre of my oil pressure switch ?? I replaced this and no more oil leaks.

Replace the PCV valve.

About a month ago I found a oil leak in my valve cover gasket so I went and replaced that and there is no leak there anymore. Then I found more leaks and went through two days ago and replaced the oil pan gasket, front main seal, and rear main seal.

And I'm still finding an occasional few drops of oil!

Where else could it be coming from?