It's just frustrating when every time this topic comes up, I respond and tell them where the disconnect is, and no one hears me.
Once again, 4+ years following this issue, never once seen this mentioned. Sorry you're upset, but I asked you to show me where you said it so that I was informed... I started this thread as a resource for everyone after all.
You still haven't shown me or anyone else
where you've said that and a search of this forum doesn't come up with anything posted by you on this topic. So,
respectfully, please don't act all butthurt when nothing is even visible here on these forums and you're going around saying things like the above.
My personal experience and evidence I've seen in friends and relative's vehicles does not denote any issue with the cap. I've never noted any residues in either of my own MK7s or my in-laws MK7. I have never once seen someone post an image of residue coming from their cap and running along the engine bay.
Maybe there is some loss from the cap, but the thermostat housing is a very real and very big problem, and I don't think the cap could possibly account for the amount of coolant people are losing so quickly.
My service advisor specifically stated that the housings warp and flex over time due to heating and cooling, and they may not always show signs of leaking during test. They tested my car twice and my wife's car three times over the course of a a few years, all while coolant was needing topped up every 3-6 months, before they actually found the housing was finally in a warped enough position to be leaking during the test. I was told that they also needed to leave it pressurized overnight in both cases.