"RichH" wrote in message ...
Common knowledge is entirely faulty.

Fuel oil when manufactured (cracked, etc.) is rendered essentially
'dry'. Water (vapor in the air) 'equilibrates' eventually until the
oil is saturated with water from the atmosphere ..... and only after
the oil is SATURATED with water does the 'condensation' become
apparent. Simple speak: if your fuel is condensing water it means
that its laid around with an open vent too long and its now LOADED
with water.

The BEST is to totally empty the tank for the winter, take home the
fuel and burn it in your heater.
EMPTY tanks dont magically fill up with water because of a mysterious
'condensation process'. :-)

No doubt that emptying the tank and the fuel system may be a good thing to do.

Since 1982 I have always stored the boat for winter (Canadian Maritime) with a full tank. At time I did add some diesel conditioner.

I never had any fuel problem. The water separator must have worked well. Now with the new boat the water separator is more Hi-Tech and I do not know if I should add some fuel stabilizer.

Last year I did not add any and I had no fuel problem. This year I am thinking about adding some stabilizer.

BTW. Over here during the winter the sun may shine on the boat and the temperature may get up and when the night drives in it gets way below freezing. I wonder what takes place in the empty full tank and conduits?