[Tembo11]

I think it's partly the Positive Crankcase ventilation that is the cause to suck oil fumes back in & burn then
Not certain why they are going against the flow unless some of it is after engine switched off

 

[Tembo11]

I think it's to do with the turbo on the boost dump as it doesn't have a dump valve! When you create boost pressure then let off the throttle you get a slight back pressure in the intake!
There is a modified hose and PCM update to cure this issue!

thanks for info about the modified hose