The concept of a "Water Wetter" is somthing that has been around a long time.
 It is especially recomended for use in Vanagons or any engine that uses
sleeves for cylinders. It is required in most diesels that are built this
way.  In addition to improved cooling, it will stop the formation and relaese
of air bubbles on the cylinder walls and in the heads.  These bubbles form
from the gases that are normally dissolved in the coolant.  When these
bubbles break, they take a minute amount of material from the metal (cast
iron or aluminum) with it.  This eventually shows as pitting that is often
confused with pitting caused by corroision.  As American Diesels have have
more vubration, heat and pressures, the effect here is obvious.  I have seen
many GM and Ford Diesels that had holes through the cylinder walls from this
effect.  The Waterboxer is also prone.  This shows up as pitting where the
head meets the cylinder.  I recomend the use of some type of water wetter.
 It is readily available at most truck stops.
Dennis.