The Noack spec' of an oil doesn"t concern me much as it has no effect that I can detect, besides no synthetic has a poor Noack.
It is important to the OEMs primarily for emission control reasons and therefore if the oil is on a recommended company list it's Noack is acceptable.
That said do we know the Noack of Castrol 0W-40? I don't think so but since this oil is on certain European car recommended lube lists it's not any higher than 9% anyway and that's probably what it is. Again nothing to distinguish it from any other approved oil.
But one further thing I do not like about about the Castrol 0W-40 vs M1 is it's low AW levels with the exception of ZDDP. So I prefer Mobil's add' pac'. Obviously this isn't a issue with the company oil lists that Castrol is on but then company certifications is just about a minimum requirement.