See attached pic.
How does Widman Curve determine these numbers at say 0c? Intuitively, M1 0w40 (blue) having a higher viscosity at 100c than M1 5w30 HM (red), 12.9 vs 11.9, and almost the same viscosity at 40c (around 70) it would be reasonable to assume M1 0w40 thicker at 0c! Curve shows the opposite!
Why it shows at 0c M1 is less viscous than the HM oil?