1997 850 turbo bad or valve seals?

[1volvoguy]

my head gasket was blown, no question. Replaced it, then still had smoke, never thought to check turbo while it was off. When I did it was big time loose, shaft had a lot of play. Car has 156,000 miles. I replaced it with a used turbo. Runs great now. No blow by, no smoke, just perfect!
Turbos can fail just from using crappy oil or not changing it enough, never know for sure. Luckily mine didn't explode, just wore out! I do agree it seems a bit early at 156K, but still, it is 18 yrs old