I have a small oil leak with my 96 850 wagon that has 95k miles on it. I am told that it is a rear engine seal leak. It is leaking very little ( I haven't had to add any oil in over 1,000 miles, but I do see a small spot of oil on the garage floor. Before I spend the large amount of money to take down the engine and have it fixed, is there something else that should be checked? Could there be a problem with the PCV that could be causing this oil leak? What is the general thought about oil additives that could "plug" up this leak?

If it is a naturally aspirated model crankcase ventilation is through what is known as a flame trap, which is nothing more than a plastic screen attached to the rear of the throttle body. Either the plastic screen or the hose from the crankcase gets clogged, resulting in excessive crankcase pressure. It is very easy to clean this yourself or replace with a new one (inexpensive). I would not recommend any type of stop leak product. My concern would be that it would cause more damage than it is curing by potentially clogging oil passages, etc. Question- Did you recently change to synthetic oil. Some folks have reported seal leaks after changing to synthetic due to the more uniform synthetic molecules getting past an otherwise weak seal.

Is it a turbo? If not, and you didn't say it was, disregard...

It could be the turbo's oil return line -- very easy to fix. You need two parts from your parts dealer (return line o-ring and return line gasket) and about an hour. And a few tools. And be able to get under your car -- so all in all it's an easy fix depending on what equipment you've got :)

The steps are on volvospeed.com

Matthew
http://www.evenfive.com/volvo