Dont think I have an oil cooler on mine, as its the most basic engine in the mk3 range, but i'll check it out.
its almost like its leaking from higher up the engine and leaking down, but where from, I cant tell, with all the belts/pulleys in the way.
Definately oil too, coolant appears to be ok. Didnt see any cracks on the bas of the engine when the sump gasket was replaced, so that rules the very bottom part of the engine out.