That is extremely well done, from a former Mobil Lubrication Engineer! Thanks for sharing an example of how to do things right!
Does anybody know why lubricant additives "have a tendency to settle over time"? I never looked into this. I thought they were supposedly in liquid solution, not liquid suspension?
Depends on the individual mixture and chemistry ( and sometimes the actual mixing process) as well as where the volume came from in the distributor tank.
Some recipes simply were not cooked long enough in the first place
Some additives simply separate from fluid pressure ( density) and time ( heavier molecular additives and some anti wear metals)- this is the cloudiness and sometimes visible layers.
Some precipitate naturally
Some polar bond with various contaminates or get heavier by oxidation from air ( or other processes) in the container.
Some can be "altered' and even filtered out by the micron rating of a filter further altering the product.