Ok, so I've started doing my own oil changes. My preference, after much review of the info here and elsewhere, is for Castrol Syntec 5w40, which is rare as hen's teeth around here.
Mobil 1 in 0w40 (Porsche approved) and 10w40high mileage is readily available and relatively cheap. If I blend the M1 0w40 and 10w40hm will this result in an appropriate 5w40 weight oil for my '01S?
Or suck it up, pay the extra, and order the Castrol in the correct weight?
Thanks in advance for the education.