Speaking just from a base oil perspective, which isn't really practical, but for the sake of calculation, it's easier, we could try and target the 12.9cSt of M1 0w-40 "FS" using a PAO base blend of the following:
1. SpectraSyn 8 - 8cSt @ 100C, 48cSt @ 40C, MRV of 16,200cP @ -40C, CCS of 4,800cP. 4.1% NOACK,
2. SpectraSyn 40 - 39cSt @ 100C, 396cSt @ 40C, MRV of 102,000cP @ -26C, CCS N/A, NOACK N/A
Using the Widman visc calc, to hit our 12.9cSt target we'd need 66.3% of SpectraSyn 8 and 33.6% of SpectraSyn 40. We could use an even heavier base and move that around a bit but the resulting product of the above blend would have the following characteristics:
100C Visc: 12.9cSt
40C Visc: 90.3cSt
VI: 141
And it is quite possible for it to be below the MRV limit at -40C. It would fail CCS though.
A blend using SpectraSyn 100 instead would put us at roughly 77% SpectraSyn 8, which might yield more favourable low temp performance, but I'm not an expert so I could be completely off-base there, LOL