On all these subject, my dad through AT&T has been to numerous
corrosion seminars, primarily about corrosion of underground pipes
or transmission lines, but other subjects as well.  This hardly makes
him an authority, but always, always it is stressed in these that metal
to metal corrosion has 1 and 1 cause only, an inbalance in electrical
potential, no matter how slight.
Indeed he has told me that a lot of the old timer Western Electric guys
used to swear to merely bolting pieces of magnesium to bare spots on
their vehicles frame, the magnesium being more reactive would dissapear
and the steel would be protected.  VW too started this putting zinc pads
under the fender bolts on front fenders, at least my Q syncro had them.
Another data point, the gold cad plated hardware on VW's a curse in
salty
areas, it is more reactive and the coating dissapears to white oxide off
of bolts, gas, power steering, a/c, and any other lines, even often on
cars
with zero corrosion on steel body parts.
I had recently been wondering about this idea of equalizing potential as
well and I for one will certainly run ground straps everywhere on the
'85
with its relatively new heads, and will run Prestone Long Life, and will
run a water wetter as well.  A little prevention never hurts.

John