Car smoking ocasionally

[daimlerush]

Hi,
I have an bmw x1 xdrive 2.0 e84 
Some time ago I was driving in town centre and noticed alot of smoke coming out from tailpipe especially when accelerating.  The smoke's colour was white/grey and smells like burn oil. I also had the oil light on after some time. I called the nearest garage I could find at that time and left the car there for the mechanic to have a look. From what he said he tested turbo, he did a comparison test, and flushed the engine 3 times. (That's what I was told and charged £500).
In the meantime car has the same problem, is smoking ocasionally and every episode lasts aprox 2-5 mins. I noticed today after driving it for aprox 30mins  that if I stop the engine and turn it back on the smoking stops for some reason. 

Things that I already did myself:
Changed the PCV valve
Cleaned the egr and cooler tank
Did an ISTA diagnostic and found 2 errors (one for EGR and one for DPF)
After cleaning the egr and cooler tank the egr error disappeared. DPF is still there.any 

I have been with this car since then to 3 garages including bmw wakefield. Noone could find the problem, everyone said everything is fine with the car. That's probably because everytime I was to their garages the car was not smoking at all.

Any ideeas on what else could I check ?

Links for ista results screenshots:
https://ibb.co/VLqz0G7
https://ibb.co/mC6vVyt