The turbo engines do not have a PCV valve, but they have the same oil breather system as the NA cars. All of that oil has to go somewhere! Either valve guides are worn, but shouldn't be at 120K, or the oil separator box under the intake manifold is plugged.
I suggest getting the kit from FCPGroton to replace the breather system, excluding the manifold gasket (buy a new one from the dealer) and watch the oil consumption go away. It is a 5-10 hour job depending on skill level, but it is worth the effort.
Also check for any drips on the ground after parking, could be a turbo oil return line seal or RMS.

Klaus
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Please answer your responses. We need to know if the advice is good or bad. The 164 has a new home, all I am left with are 2 turbos :)