Thanks for the input guys.
Just to clarify, I'm using 0.75 qts every 500 miles, not 3 or 4 quarts (could be misunderstood based on how I typed it above, my apologies). This is an increase of about 66% from what I've seen in the past. According to Subaru, oil consumption less than 1quart per 1K miles is "normal".
I did replace the PCV valve at 60K and can do that just to make sure, it's cheap and easy. That being said, since I can't find any oil anywhere I'm guessing this isn't the cause.
I'm skeptical of compression test results (when I do the test, never had results that made sense). I called the stealership and they told me they charge $450 for a compression test
At least if I decide to do this they'll install new plugs at the same cost.
I'm still on the stock turbo so it's possible (and hopefully most likely) that's the cause. What failure modes would I see if it's the turbo? Would checking the shaft for play (by removing the down pipe) tell me if this is the issue? I'll also see if I can get some help from a friend to confirm I'm not blowing blue smoke.
Not sure how I could tell if the cam seal is junk... any thoughts?
Hopefully I'll be spending money on a new turbo/stage 2 mods instead of making sure my car is functional...