This is a known issue with the Subaru boxer engines, worse on some years/models than others. They generally last longer if the maintenance has been done by the book, but this is one of the only engines where a head gasket is considered a maintenance issue.
Bikesnale, may I suggest selling it and cutting your losses? Not much point in dumping $3-4K into a nearly 10 year old vehicle in order to sell it for $8K.
My 2002 Legacy is still doing well in the head gasket department at 195K, but it's getting to be time for me to sell it…
Yes it's a big expense. Unfortunately cars are a gamble. It's get it fixed, drive it for another 100K hopefully will be problem free. Or dump it for cheap and buy another car. Either way one has to throw down. The old catch 22, hope it works out.
BTW I drove mine for a year before doing the heads. The leak was super minor, just that it leaks right onto the exhaust manifold and the smell drove me crazy.
One last thing DO NOT try the stop leak stuff in a bottle. Will screw your car up big time.
People always ask me what's the phenomenon
Yo what's up? Yo what's goin' on- Adam Yauch