This is getting ridiculous. Telling people I am confused does not make it so. And again we have more errors with which I have to deal.
As I said before, beware of extrapolation, particularly with thermally triggered chemistry. Just one example I'll give is the Mobil 1 0W50 with a VI of 189 and HTHSV of 3.8 compared to Millers CFS 5W40 with a VI of 177 and an HTHSV of 4.4. Mobil1 has the higher VI, lower HTHSV, is heavier at 100C, but thinner at 40C.
For a given HTHSV would make it even moreso. For simplicity, I'll just use the lever rule. A 60/40 combination of 5W40 and 0W30 will give an HTHSV equal to the M1's 3.8. Now my lower VI, which results in 175.4 oil should be even thicker at all temperatures below 150. But it isn't. kV at 100 is 12.84 (M1's is 17.2).
Let me repeat what you said that is proven wrong by the above example: "A lower VI for a given HTHSV is a heavier oil at all temp's below 150C,"
Again, NOT TRUE.
Why? Because VI is quantified based on KV at 40 and 100 degrees. Extrapolating with thermally triggered chemistry is foolish. Disagree? Take a look at this chart - oil film T and CF versus temperature of a competitor:
Take a look at the oil film at 40C and 100C and then again at 150. You can NOT extrapolate. But the absolute statement made previously about the relationships between VI, HTHSV, and KV can only be made by an assumption that extrapolation is safe.
At this point I AM confused. But not about oil.
If my speculation of the content of the Castrol's base stocks and VM's reflects a lack of understanding, then show me how you do it.
Millers 10W60. HTHSV is 6.0cP, and KV at 100 is 24.4cSt. Without speculating, please tell me what the base stock and VM composition of the oil is. "There is no confusion here. Different oil chemistries have different oil-viscosity coefficients."
Tell you what, if you can lay it all out, I'll go away.
I won't even ask for you to explain how HTHSV is the only important number to a hydraulic system operating at approximately 100C using unpressurized oil, but whose flow is controlled via reed valves and torque oscillations.
I also won't ask you to explain to me why the calibrators who control the system need to know the oil temperature, but not the pressure.
If you can't meet the challenge, the answer to the hydraulic system is not "you are confused, you can ignore kv at 100C." The term "Reynolds Number (Re)" may help shed some light on it.
I will agree that HLA's are not nearly so sensitive to viscosity changes.
Oh, and BMW specifies Castrol TWS 10W60. I do not know what the factory fill is, but it is considered a break-in oil that must be changed at 1200 miles. I do not know how that (PCM) system works. It may not have a CTA VCT system. It may be a conventional one, which makes the whole discussion moot. The PCM may have multiple tables that are changed when the car goes in for service the first time. I don't know (and yes, I will freely admit when I do not know things).