rust prevention - sacrificial anode?

IMHO, no. This works in water because the water is an active electrical conductor and completes a sort of voltaic cell between the two metals and the water itself. Car corrosion is almost always happening in tiny places where just a spot of water collects unknown here and there and starts a little pit underneath. Sometimes these pits can get sealed over with oxide waste, and keep working deeper even if the "surface" looks like it is dried out. I think keeping it clean and out of the water as much as possible would be more effective.

Now somebody say that maybe it would have worked on an Amphicar!

 

I don't think zinc anodes would do much for a car. They're used on boats to protect bronze and aluminum parts from electrolysis. Dissimilar metals in a conductor,i.e. water, act like a battery. One metal will give up its electrons to another. Let it go on long enough and the metal will turn to powder. Zinc is a less "noble" element than others so it gives up the electrons first.

Rust is a somewhat different electro-chemical process. It's oxidation.

Having said all that, I have seen a device that, if memory serves, sends a low voltage current thru (or on) the metal parts of the car to prevent the rust process from starting.

 

The downside to adding zincs to your car is that they work in a smaller area than one would think. They have an effective distance they protect, but it is fairly small. This is why zincs are used for the lower units on outboard motors. They protect the small amount of metal in the water.

 

J.C. Whitney, purveyor of all gimicky automotive things sells (or sold) this system.

Seems like FM to me. Never heard of anyone that tried it.

I severely doubt that it will work.

 

They would work great if you stored your car underwater.



Darrell.