So you know how supposedly the yellow dipstick is a fix for the old orange one that crumbled to bits and fell into the sump?
Turns out it isn't. I suggest keeping an eye on yours. I think I will replace it every 2 years as a yet another TFSI consumable item
I also discovered the supplied O ring is slightly too small and causes a small vacuum leak. I fitted a larger one and it seems to have cured some snatching/surging I was experiencing at very light throttle below 2000rpm. I'm investigating silicone O ring options as they're less prone to deterioration compared to the standard nitrile rubber o rings.
It may seem like the o ring was doing it's job going by the colour difference before and after the ring, but believe me, there was oil on top of the dipstick tube, meaning boost blew it past the ring.
The cracks you see here resulted it those bits separating and falling off with gentle pressure. They were destined to end up in the sump, so I caught it at the right time.