So looking at the Mag-1 we get a viscosity index (VI) = 102, for the Amalie SAE 40 VI = 102, both listed values and both API SP oils.
Calculating the VI for the Carquest SAE-40, using the VOA viscosity figures, I get VI = 136. This is a bit too high, and puts it in Group III territory, which I don’t think is possible for a SAE-40, however the VI is obviously over 100 which to me means it’s Group II.
To me this is where these newer SAE-30 and SAE-40 monogrades shine, sure they have an API SN or SP add pack with a LSPI friendly Ca + Mg detergent package plus regular zinc levels of about 800 ppm, but look at the pour points (PP) and think of the improvement in oxidation stability compared to the old school Group I monogrades.
Mag-1 SAE 40 PP = -30C / -22F
Mag-1 SAE 40 VI = 102
Amalia SAE 40 PP = -33C / -27F
Amalia SAE 40 VI = 102
With the corresponding SAE-30’s doing even better.
For comparison Castrol GTX 20W50 has a PP = -30C, and J300 says it can pass the cold cranking (CC) test at -15C. Sure PP isn’t CC, but if I was running a modern Group II monograde and the temperature dropped a bit below freezing then I personally would not be concerned. In the old days of Group I monogrades, I would be far more nervous.
You also have the benefits that a Group-II has far more oxidation stability (over Group-I) so this allows a longer oil change interval (OCI) than was possible in the past. I personally would be OK with a 5k miles OCI on a modern monograde for my application.
Monogrades have no polymer viscosity index improvers (VII) added to the oils, which means 100% shear stability and less engine contamination.
Also look at the Noack volatility figures
Mag-1 SAE 30 = 5%
Mag-1 SAE 40 = 2.8%
To me, if you live in a warm climate, a modern monograde is worth considering.
I’m putting my money where my mouth is, a few weeks ago I purchased some Penrite SAE-30 monograde (VI = 113) and that will be going into my car for it’s next OCI.