Soooo I've been trying to track this problem down for a while. Leakdown test shows 5,8,5,10. Consumption has remained the same through 3 different turbos I've had on the car. Valve cover gaskets are leaking, and PCV valve is original. I'm going to change those two and monitor the situation. Oil is Rotella 5w40, switching to Castrol 10w30 at my mechanic's recommendation at the next oil change.
Anyone want to take a crack at this one? I'm at a loss for what could be consuming this much after the leakdown test.