Mobil 1 0W-16 is virtually all PAO, the most expensive base stock.
0W-16 is 0W-20 with less viscosity-index improver (VII).
Therefore, 0W-16 is nearly a monograde.
Expect A_Harman index ~ 0.98. I expect the base-oil quality index (BOQI) to be over 100. Current 0W-20 BOQI record (also by M1) is 84.
It's quite evident that manufacturers need to uniformly increase the base-oil quality as the viscosity gets lower. This is so that the oils can still meet the performance requirements as they get thinner. M1 0W-16 is virtually all PAO, which is unseen in API/ILSAC oils since the SM era.
In addition, 0W-16 features the newest antiwear/extreme pressure/friction modifier (AW/EP/FM) technologies to make up for the decreased viscosity when/if needed for the different lubrication regimes in the engine.
The long story short, if your engine is designed for 0W-16, you will be running the best oil out there.
(Mostly) M1 compositions:
Note: The remaining balance (percentage) is ester (probably 0 - 10%), Group III, viscosity-index improver (VII), and additives. Base-oil quality decreases as PAO > GTL > Group III > Group II > Group I.
M1 0W-16 SN: 70 - 80% PAO, 10 - 20% GTL
Mobil Super Synthetic 0W-16 SN: 70 - 80% GTL
M1 AFE 0W-20 SN: 30 - 40% PAO, 10 - 20% GTL, 30 - 40% Group III
M1 EP 0W-20 SN: 60 - 70% PAO
M1 AP 0W-20 SN: 60 - 70% PAO
TGMO 0W-20 SN: 80 - 90% Group III
M1 5W-20 SN: 40 - 50% GTL
M1 AFE 0W-30 SN: 10 - 20% PAO, 20 - 30% GTL, 30 - 40% Group III
M1 5W-30 SN: 20 -30% PAO
M1 EP 5W-30 SN: 20 - 30% PAO
M1 AP 5W-30 SN: 5 - 10% PAO
(Compositions from
ExxonMobil MSDS)