Having been following this thread, and having asked a few questions, I bit the bullet and removed the intake manifold on my GDi. It's a 2020 with 9300 miles on the clock. Needless to say I found the valves had carbon build up, however the no.1 cylinder (nearest the rad) was particularly bad - maybe due to the rusted spark plug on that cylinder?:
![[Linked Image]](https://www.tm-img.com/images/2023/12/21/plugs.md.jpeg)
You can see the before and after pictures of each pair of valves:
![[Linked Image]](https://www.tm-img.com/images/2023/12/21/valves.png)
I decided to fit a small catch can and re-route the vent from the sump via the catch can. I know some people have done this and have then vented to air, however I decided to vent back into the inlet manifold. My thinking is that the car has been designed to have a negative pressure in the sump, and the vacuum from the inlet manifold will draw the oil mist and fumes into the can. Only time will tell if it works, but at least I feel I am trying to do something to keep he valves cleaner than they would otherwise be.
Hose connection to the outlet from the sump:
![[Linked Image]](https://www.tm-img.com/images/2023/12/21/outlet.md.jpeg)
Can installed with pipework:
![[Linked Image]](https://www.tm-img.com/images/2023/12/21/can1.md.jpeg)
![[Linked Image]](https://www.tm-img.com/images/2023/12/21/can3.md.jpeg)
![[Linked Image]](https://www.tm-img.com/images/2023/12/21/can2.jpeg)