Wait. What "handbook" calls for 5w30? In most cases any reference to 5w30 in a European car actually means a heavier Euro 5w30. VW 502 reference charts are numerous and confusing, plus there are errors. Normally, any 5w-40 is a a great choice in a Euro car that needs synthetic oil. For colder temps, 5w-40 is actually somewhat thick, even for a normal engine. Early 2.7tt engines had relatively small oil lines to the K-03 turbos. That was corrected later on.
Still, I feel 5w-40 is to thick in winter and in your case, too thick unless your mom is some crazy Autobahn Baroness. See, that grade is for crusing at 130 mph all day, not cold starting to run out 2 blocks for some cocoa in New England winter. This is especially if she does not observe proper warm-up.
So, that takes us back to actual viscosity at start and operating temps. A 0w-40 like m1 and a 0w30 like GC are good, but I think you can even go thinner, back to thin American 5w30 like Pennzoil Platinum....the thinnest of the bunch! If you like PP in winter, then maybe go with another Shell product, Rotella T 5w-40 for summer and do only 2X a year changes. Trust me.
btw- I've see a great UOA on Pennzoil Platinum 5w30 in a Audi 1.8t, fwiw.
