My T5 doesn't smell or even use any oil between changes. It has had it's return line "O" ring replaced. Symptoms: gushing oil over the rear of the motor. That's an extremely common, almost universal failure. It should cost only a few bucks. Under $10 for the parts if you do it yourself. As others have said, the turbocharger itself should last as long as the rest of the car. Turbocharger failures seem to be less common than even engine failures. See:

http://www.volvospeed.com/Repair/turborepairline.htm

Find a mechanic who knows Volvos.

-Punxsutawney Phil