On Wed, 13 Apr 2016 10:37:48 +0700, John B.
wrote:



I have no idea of how effective the units for automobiles but I can
assure you that the similar systems used on buried pipelines are very
effective, certainly far more than anodes. I also understand, although
I've not seen it my self, that all very large shipping use the system.
Well I have a real good idea how well they do NOT work from the 3
examples I provided. They were a pretty common "aftermarket upsell"
at many dealerships when I was in the business - and the dealer was
the only one who got any advantage out of the sale other than the rust
warranty (if it was vallidated by paying the dealer an annual
inspection fee) - and even then it seemed the vehicles with the units
installed needed a lot more rust repair than those that didn't -
particularly those that got an aftermarket oil / wax type rust spray.