Yes, oil can leak from the turbo into the intake, but usually will also
leak into the exhaust -- if so, there will be quite a bit of coke in
there (hard glassy carbon) that is fairly oily, not dry and fluffy.
The other source of oil in the front of the turbo is blowby and/or a
failed oil separator allowing oil mist into the intake rather than
returning it to the pan.
Most likely excessive blowby -- have you pulled the hose and checked?
I've not been following this thread carefully.
If OK, I would suspect bad valve guides -- you have to put enormous
amounts of oil into the combustion chamber before you get blue smoke on
a diesel.....
Peter
