I had two on my 98 T5: First was there from the factory and was a leak associated with the plumbing for the oil sprayed against the bottom of
the pistons (high pressure turbos had this in 98; later, they all have it).
I think this is very uncommon. Fixed first week of ownership and no
further problems after 5 years. Second was from the oil pump cover's
screws. Dealer caught it at 10K service. Known problem on 98s. Fix is
to back out each screw and re-seal it (or a new gasket, not sure). No
problems since fix.

Oil leaks from the turbo drain line are also very common on 850 turbo
models (not sure if 70 series see this as often). Cheap and easy fix.

Oil is often spilt down under the plastic cover (on top of the engine)
when adding a can of oil. It can puddle there and you don't see it til
you pop off that cover. I guess a big spill could leak out (but it would
have to be a pretty big spill). Technically, not an oil leak.

Our 95 850 wagon has never leaked oil -- it just burns a quart every 4K
miles :)