Oil pressure question...I promise it's not another "who likes what' thread!

Here is a short link as to what VI improvers do. Pay careful attention to what they do with temperature. https://www.machinerylubrication.com/Read/29842/viscosity-index-improvers

You can’t have a multi grade oil that doesn’t act like the upper grade with temperature or it would be a single grade oil.

In fact, there are some single grade oils that are not really single grade oils, but have to be sold as such because either API or SAE (could be both...I just don’t remember which it is) doesn’t recognize winter grade oils above 25.