Recently bought 1997 850R. Currently 111K. Dealer (not Volvo) had on lot said there was an oil leak but they couldn't find it even after adding die. Checked with local Volvo dealership. Car had been serviced there. Records showed oil trap cleaned and other work done to reduce crankcase pressure at 96K. They were not aware of a leak. Did not drip in first few weeks. Now is fine for days then will suddenly dump enough oil to make a long slick, drip for a while and then clear up. Seems to happen after short highway drives to work on cold mornings. Maybe has something to do with when the turbo kicks in? Any ideas about what could cause and intemittent leak?