Turbos can consume suprising amounts of oil. But usually it smokes like a bastard. I've had bad valve seals cost me one quart of oil per one tank of gas, with ZERO smoke. Good luck diagnosing this over the internet. And losing a few quarts per oil change is a far cry from losing a motor, don't panic yet
80k is a little soon to need valve seals, but well within the normal mileage when stock 2G turbos can eat shit. Check the compressor housing inlet for oil residue. A little film is ok, a puddle is not. If nothing is there, I would pull the turbo and look for oil in the turbine housing, though this tends to be the smokey version I mentioned above. Worth a look though, a turbo is an easy fix compared to the other possibilities.
I would check the compression too. That might have something to say about how hard the motor has been worked.
Clogged PCV valves are another common source of smoke and oil loss. And another extremely cheap and easy fix. I would replace it just for the sake of ruling that out.