Originally Posted by RotaryResurrection

The way I check for oil seals in the engine vs. a bad turbo is to pull the turbo and check the exhaust ports of the engine. They can be read on a rotary just like sparkplugs. Tan equals no smoke from engine. Black equals oil burn smoke or rich burn from engine. IF you have a smoking car and the exhaust passages (prior to the turbo, obviously) are tan, then it is NOT your engine.

Furthermore, I've plugged the coolant holes and used a hose to temporarily mate the oil inlet/outlet from the turbo, rerouted my intake, and fired the engine up shortly without the turbo. Yes, it's damn loud, but it's a definite indicator of whether smoke at idle comes from the turbo or the motor.

Originally Posted by Reted

As people have mentioned, the "purge valve" on ours cars works as the PCV system.
If the crankcase isn't relieved of pressure, this cause the turbo to smoke, usually.
I had to troubleshoot several members who have contacted me about this, and this was usually the root cause.
Several of them were getting overenthusiastic on pulling emissions, and just managed to pull and plug both fittings on the oil filler pipe, one lower by the engine and the other higher by the oil filler cap.
This will cause excessive pressure to build-up in the crankcase, and the turbo will usually start to smoke.
An easy test for this is to remove the oil filler cap and drive around.
Drive easily to keep the oil from sloshing up the oil filler neck and making a mess!
If the smoke stops, you need to vent the crankcase or put back the purge valve system.

The quick&dirty test for the oil control rings is to rev the engine up to about 3k to 4k for at least 20 seconds.
If it smokes more, it's the oil control o-rings.
The increased vacuum from the high idle pulls the oil past the dead oil control o-rings, and this causes more oil to burn and smoke.

Check your intercooler hoses.
If it's coated heavily with oil, the turbo compressor seal died, and oil is being sucked into the compressor section.
Turbo needs to be rebuilt to replace the bad carbon seal.
The symptoms for this problem is intermittent heavy smoke out the exhaust that stops suddenly.
It's usually inconsistent and very hard to replicate easily.
This is due to oil pooling in the intercooler, and when enough of the oil has accumulated, it all gets sucked into the engine to burn.

Check your spark plugs.
If the turbo isn't spewing oil out the compressor side, and the spark plugs come out clean, then it's most likely the turbo has a bad turbine (piston compression) ring.
Turbo needs to be rebuilt to replace this ring.

This is my typical procedure to troubleshoot excessive oil smoke out the exhaust...