My first thought is for the crankcase pressure building up. Most often that
shows up first at idle, causing billows of blue smoke when idling and for
about 30 seconds after taking off. When the crankcase pressure builds up the
oil backs up into the turbo and dribbles into the exhaust.

Remove the oil filler cap, then unfasten the hose that crosses over the top
of the engine from where it attaches to the side of the turbo intake duct
and try blowing through it. The resistance should be a bit more than you
would expect of the hose itself but not as much as if you were trying to
blow through a soda straw. You should be able to exhale in three seconds or
so. If it does not flow freely, check the hose pieces (no fooling!) and the
oil/air separator box it attaches to under the intake manifold. That box is
held by two bolts and the friction of the two o-rings beneath it. If the box
is plugged it can be cleaned, but not well and not easily. Replacement is a
better alternative if available.

Mike

I forgot to mention - that oil pervading the intake system is normal for the
740/760/940 turbos. The crankcase ventilation system sucks the mist out of
the crankcase and reintroduces it ahead of the turbo. It collects in the
intercooler and coats all the ducts.

Mike