One other possibility. Did you look at the bottom of the induction line running from the turbo to the intercooler? This sometimes gets soft or cracks directly above the turbo. Because the oil seal is less substantial on the induction side (they're not worried about oil as it will collect in the bottom of the intercooler), engine oil can mist onto your engine there. Even then, you'd smell hot oil as some of it would spray onto the hot heat shields and the turbo.

Unless you've had a major engine overheating experience, I'm convinced your problem is not the turbo.

100K miles is not much on late model Volvo turbos, and turbo failures in FWD Volvos are rare. Look for other, more likely causes first.