From your pictures it's clear that you have leaking injector seals (chuffing injectors). The horrible diesel fume smell is evident of exhaust gases leaking past a small copper washer, this seals the injector into the combustion chamber. It does NOT affect engine oil or come in contact with engine oil.
From your pictures it looks like it been leaking a long time. It will be difficult to remove the injector and clean, you should be able to do just the one leaking seal. The head/seating will need to be reseated and all that crud removed. Don't buy seals from Ebay.
Last edited by G-A-R-Y; May 8th, 2019 at 08:47 PM.