Rear main seal failures are common on these 850's. My '95 (106,000 miles) started leaking suddenly a couple of weeks ago. My local independent Volvo mechanic charged me $550 to replace it. (Dealer cost would have been about $900) I used this opportunity to replace the lower radiator hose and the lower engine mount. The puddles of oil were directly under the rear of the engine (inboard of the drivers side front wheel). However, I didn't notice a lot of oil splattered under the car when I found it. Good Luck - I hope you leak is something simple.