2006 Subaru Outback Question for mechanics?

It would have to be a cam or front main (crank seal), since the tensioner does not hold enough fluid to create a noticeable leak. Whoever put the belt on probably cleaned up in there, stopping the drip temporarily. BTW, the front main seal is on the oil pump (the oil pump slides over the crankshaft). I would pull the outer timing covers off and check the cam seals, you should be able to do that w/o pulling any belts off. If the cam seals are good...then you know for sure the crank seal is shot.