[myskyon]

OK this is starting to scare me as people are saying the AOS is bad. or the seals are bad. it very well could be the turbo seals are going and that is where the oil is coming from. there is a very simple check for this. and that is to remove the breather hose off the J-boot and see if it has oil dripping out of it. if its dry as a bone then your turbo is the culprit.
I have an 87 951 that the turbo seals are bad on, blows smoke under boost, but you cant see it through the black smoke. Also I have another 951 that had a bad cam tower gasket. leaked oil onto the top of the motor as well as a little down the back. replacement is not hard. took about 4 hours being very very carefully and BS'ing a lot.