I recently had to have my inlet manifold and valves decarbonised.. dpf was good.was told to fit a catch can to stop the oily smoke from the crankcase entering the inlet manifold.do catch cans work???.I have a 2018 diesel outlander and don't want this carbon problem again.ive been told it's a common problem with this motor

 

Yeah, oil/diesel separating can works prefect on my 2.2DiD diesel.
But avoid squeezed/bent hoses by using metallic tubes inserted.