Probably some readings and comments over the years.
Generally talking, Mercedes for example , that I know well enough, is only selling antifreeze that you mix with distilled water.
Bentley is doing the same, Porsche too, others major brands too.
Mercedes as a special antifreeze we several actions.
When you mix a quality antifreeze with distilled water, you know what you mix as you are supposed to know the quality of your antifreeze and there are many standars, from low to high quality.
When you buy a premix, you don't know what kind of antifeeze they use, and most part of the time, this is a medium to low quality.
Of course pre mixed is much more simple, no preparation, no mistakes, but the seller makes double profit because he premix for you and above all , use an unknown quality antifreeze to mix and generally talking a cheap coolant to make more profit.
In our time, if you want quality, do the things yourself....
Of course there are certainly some high quality premi, but of course they are not the majority and you will pay the company who prepares it for you.
All the quality brands I know recommand you do your mix because this is the best way to use a high quality antifreeze which is very important for engine protection.
Coolant is as important as oil, as surprising as it may seeem.
97 Continental R