What is the best way to diagnose an engine oil leak? It is a 93 Grand Cherokee 4.0, and leaves a mark about the diameter of a pop can every time I park it. What are the common causes of oil leaks on these vehicles and what's the best way narrow down where the leak is actually coming from?

The ZJs are notorious for leaking oil. One good place to look would be where the transmission meets with the motor or at least in that vicinity. The rear main oil seal has a reputation for leaking. I currently have that issue, but haven't had the time to tackle the beast, so I buy alot of oil!:2cents:

Mine did the same thing. It turned out to be the oil sending unit. SJ

It appears to be leaking between the oil filter adapter and the block. There is a single Torx 60 bolt that holds it on but the bolt head is stripped. In the meantime I am going to try a little rtv silicone on the spot that leaks as a short term fix to keep oil off the driveway.