Any water that gets into the tank (emulsion, condensation, etc.) will
settle to the bottom. A bacterial broth will form at the interface
bewtween oil and water, such bacteria will use the zinc as part of their
nutrient source and eventually penetrate the zinc layer. Penetrated
zinc etc. coatings will corrode FASTER than bare steel/iron in the
presence of free water.

Its OK to use a steel or galvanized tank; but, you need to add a pumped
recirculation drop-out "pot" (free water) and water absorbing filter set
(emulsions) to be sure the water is removed (from the tank bottom) ...
and run the recirculation filter set on an almost constant basis. Such a
filter 'train' will be much cheaper than the large $difference between a
stainless and an iron tank ... on a BIG tank.

brian clode wrote:
I have been told that you should not do it but Can anyone explain why you
should not put diesel fuel in a galvanised fuel tank. What happens?
Brian