1993 945T with 120K miles. On a recent trip (800 miles), the car lost about 1.75 quarts of oil. The bottom is coated with oil and I suspect some is coming from the rear main seal. I also have noticed that the oil separator box (breather box) is wet with oil. The valve cover, front seals, and distributor seal are all recently replaced and okay. Historically, for the last couple of years, the car has lost some oil - about 0.5 quarts over 4000 miles. On this trip, the turbo was working hard - we had five bikes on top and the way-back was fully loaded with ~600 pounds. Driving at about 70mph. So the turbo gauge read positive pressure for almost the entire 800 miles. I assume that I need a new breather box because of the oil around it. (It is not plugged, however, and the other hoses for the flame trap-like thing on the turbos are okay). My question is - should I also replace the rear main seal at this point? Or just replace the oil separator and see if this fixes the major leak? We use the car mostly for long trips in the northeast and don't want to have mechanical problems (three children under 7). Do I understand the system correctly in that oil is more likely to leak out when the turbo supplies positive pressure to the intake? I am using Mobil-1 10W30 and have been for 4 years.

Thanks,
Steve