1995 Nissan 300 ZX mileage: 150,000. The rear engine seal has started to leak oil, noticeable only in very small puddles when parked overnight. As yet (for at least a year) this hasn't affected the clutch at all. Changing the oil helped for a while, as did replacing both PCV valves, but the leak is back. Any ideas? I sure don't want to have to pull the transmission and replace the seal if I can get away with it.