Have you checked the rubber plug on the back of the head? I've had these blow out and dump oil. However, I've not had one start to leak and then stop. It's woth checking though. Feel around in back of the head at the level of the camshaft. If there is oil, either the cam cover gasket or the plug is leaking.

I charge 4 hours labor to hang a rear main seal. In my shop that equates to $280.00 @ $70.00 per. Another $25.00 or so for a seal and some parts cleaner. A pan gasket on the same would run about 2.5-3.0 hours plus the parts. It could be your pan gasket but is more than likely your rear main seal has popped out. Although with a clean and clear crank case ventilation system they usually will not pop out like that, but I have seen it happen, especially when someone has used an non-Volvo seal in there. Elring and a few others make some good looking seals but I highly recommend that you spend a little bit more money and put in a factory rear main seal. For one thing you can just about push the aftermarket stuff in with your thumbs (no b.s.) and the factory stuff you definitley need to drive in with a hammer and hopefully the factory install tool, although it can be done without. If you change out the pan gasket I recommend the factory stuff as well. Whenever you are doing stuff that is labor intensive like dropping engine oil pans and transmissions it is always best to go back together with the best parts (read that as factory Volvo only) you can get your hands on. It makes no sense to save a few bucks on a part that costs you hours and hours to put in or a few hundred bucks.

Mark

Before knowing cost the source of the leak must be pinpointed. It is strange and unusual to have a gusher, have it disappear and show no loss of oil on the dipstick. I you sure it was engine oil? Could it have been tranny fluid?
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David Hunter