Just some comments about antifreeze and radiator additives.
One fact is that antifreeze will not transfer heat as well as plain water, so an engine will run hotter especially in the summer temps, usually 5-10 degrees more than plain water. We have seen temps drop up to 20 degrees when replacing antifreeze with water and RMI-25.
With over 40 years of auto service in the desert, only one additive which has proven to be the best in protecting the cooling system, and this is RMI-25.
There are 2 significant factors with RMI that make it unique, first it is the only product that will clean the cooling system while driving without being acidic or caustic which will cause corrosion in the system.
Second, it contains all the properties to properly lubricate, condition and lubricate all the areas and parts in the system. Most all others additives like Waterwetterr WILL go corrosive, or not properly provide all the protection needed, especially when aluminum parts are in contact with coolant.
Since RMI does such a good job cleaning rust and deposits, and keeps it in suspension, it should be changed yearly, and sooner when first used.
For those in cold climates, you can still have the protection of RMI when adding it to your antifreeze.
The additive package in commercial amtifreeze is very minimal, so adding RMI is very beneficial there as well as providing better heat transfer.