2011 BMW X5 v8 n63 came to our shop smoking and a dead misfire on cylinder number four, we removed the spark plug I noticed it was oil soaked I also noticed there was a lot of oil on the intake of that I then decided to check compression which tested good on all the cylinders and I was curious why only number four was oil soaked number three was partially oil soaked it turns out because the intake manifold which is on the bottom of the engine is slightly angled backwards therefore most of the oil is towards the rear cylinder if he continue driving it could have sucked up plenty of oil and Hydro locked the engine. So cylinder number three was picking up just a little bit of oil and cylinder one and two were a little bit higher and therefore did not pick up any oil
I then removed the turbo charger charge pipe and found the proof!
So the important thing to note here is that the oil is now filled up in the intake manifold just replacing the turbo would be a blind choice you need to remove the intercooler and throttle motor on that side of the engine and make sure you reach inside the intake manifold and suck out all the excess oil
and keep in mind The catalytic converter and oxygen sensors are oil soaked as well and could go bad very shortly so technically they are associated with this problem.