Just went for a long drive in my '85  and realized again why we all love
these things...also had lots of time to think...
has anyone ever tried using some sort of sacrificial anode in the water
jacket to reduce/elimate the reduction/oxidation reaction that results
in pitted heads and leads eventually to leaking heads?  i.e. electric
hot water heaters last for 10-15 years without rusting/rotting partly
due to the sacrificial magnesium or aluminum anode that is placed in the
tank.  The anode gets reduced but not the tank as the magnesium or
aluminum is preferred in the red/ox reaction to the steel tank or tank
lining.  Similarly, underground storage tanks are protected by using
large Zinc blocks that are strapped to the tanks.  I believe ships use
something similar, or at least the concept is similar.
Perhaps some dissolved zinc in our coolant would work, being preferred
in the red/ox reaction to the aluminum of our heads?  Any chemists or
metallurgists out there who could comment on this?  I am not certain of
all the details but I believe the concept is correct...although if it is
wouldn't VW have simply added this "anode" material to the Autobahn
coolant to prevent/eliminate the leakage issue and all the irate
wasserleaker owners...have changes been made to the coolant since the
leakage problem arose?  I suppose that would make regular coolant
changes absolutely mandatory to insure that the "anode" material has not
been completed consumed by the reaction.
Mark