2001 V70XC Intermittent Oil Burning

[MattHenning]

My V70 has 182,000 miles on it. I've been experiencing some oil burning smoke that only happens occasionally. The smoke occurs from the tailpipe when the car has been running at idle for five minutes or longer. This does not always happen, however. Usually it idles fine with no smoke. When it does start smoking, though, it smokes a lot. Every time it has happened, the car has been at normal operating temperature. The oil I use is Mobil One Synthetic. In the 5000 miles since the last oil change, the car has used half a quart.
I have put a plastic bag over the dipstick tube and observed a very slight vacuum. I am assuming that this means that the PCV system is working properly.
I have a notion that it could be the turbo. Is that possible or likely? If so, why would it be intermittent? Is this a common problem? How difficult is it to remove and replace the turbo? (My mechanical skills are such that in the 20 years I have been driving Volvos, I have never taken my car to a mechanic.) Could I rebuild the turbo myself, or would I be better off finding a used one?
Lots of questions. Thanks in advance for your time.