Originally Posted By: tig1
Why 0-16? Why not 0-15, or 0-17? I don't get it.
Where you been tig1 ?
The Japanese OEMs, spearheaded by Honda wanted lower viscosity grades. Honda even sold those oils well before they had a grade available, and Toyota in one version of TGMO appear purposely to have made it shear down to around 2.4 early in the OCI (results reported by CATERHAM).
"20" was an incredibly broad range, which meant that it was virtually impossible to shear out of grade, thus they mythology that "20s were incredibly shear stable".
So the SAE split 20 into a couple of parts, and introduced 16, 12, and 8 grades, all with progressively lower HTHS, and some overlap in KV.
They chose 16, 12, and 8, so as not to confuse with the "W" ratings, like 15W, 10W, 5W.
Oils have been on the market for quite a reasonable amount of time, and as can be seen by the PDS of this, Ravenol, and the others, the VI is quite "moderate", meaning that they can get their HTHS derived economy without pushing for stratospheric VIs.
Assuming that this is brewed to the lower range of the allowable HTHS, it's ratio of high shear to low shear viscosity (Viscosity Modifier Impact) is quite small compared to the Japanese 0W20s.