Zeus: best bet would be to clean it up real well, and then start it up and watch for where you see contamination. they sell dyes to look for leaks, but given the location of your leak, i would think seeing anything could be problematic.
it can be hard to pin point leaks like that since in driving, the turbulence of the air can fling oil all over. hence the test above. good luck.
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Michael, dont get me started on that Porsche. got it with 12K miles. had a bad turbo seal at about 14K. dealer swapped it under warranty. then went through 2 more sets of turbo seals by the time i sold it at 25K miles. the return line was poorly engineered (almost a flat run back to the sump) and coked up quite a bit. air/oil cooled turbo also cooked the oil, leaving me little pressure (oil light came on at one bar). back then, i was not savvy enough to run an oil cooler. Mobil 1 was fairly new, and did not help much. i even ran 50 wt once.
i would have converted to an independant oiling system with a turbo timer were i to do it again.
and dont get me started on the external wastegate. i got a bad rattle and thought i broke off the platinum, palladium, rhodium in the cat. get in there and find that the waste gate shaft had worked the seat and gotten some slop (so that as exhaust pulses went by it chattered the "door" on the wastegate). take it out and have a shim machined for it. loads of fun. NOT.
that car was a pain, but what a great road car. and back then, the
Pirelli P7's were very pricey. the whole car was expensive.