When the seals in a turbo are going bad, usually the symptom is a LARGE plume of blue smoke on startup that lasts a few seconds and then goes away.
The reason for this is that when you park the car at night, oil will be seeping past the bad seals and into the compressor housing. Once you start the motor the next morning, the impeller wheel blows all that sitting oil into the intake of your motor and you burn it off over the next few seconds.
If you don't have a huge cloud of blue smoke on cold startup, your turbo seals are likely just fine.
'97 E300 Diesel (daily driver)
'87 Porsche 911 (track car)
'02 Porsche 911 (weekend toy)