Look back, I said: "Actually a multi-viscosity oil is just the opposite. It is an oil that has its viscosity stabilized (in other words it is mostly the same viscosity all the time). So it can be thin when thin is cool and thick when thick is hot."
It isn't deciding to be one thing one time and something else later. It is a "Statement". It is trying to show how a particular type of oil does differently than previously. In other words: Old dino oil, 40w. When it is cold it is actually 90w (example only), when hot it is actually 10w. Now we look at viscosity stabilized oil (multi-viscosity is the term). When cold it probably is probably 40 weight, when hot about 20w. Its properties at cold temps are like those of a 15w straight weight oil. Its properties at engine temp are similar to a 40w oil. The range is different.
I hope you are getting this as I am getting confused (bg).
Bosch Master, ASE Master, L1
33 years MB technician