Stainless steel rocker panels

[Gromit]

I like this stuff - believe it is a mixture of a paraffin or wax based substance and a solvent - so it flows into any crevices and blocks off the oxygen to help stop the rust from continuing or getting worse anyway

Available at Home Depot so that helps...

And it has a straw on the aerosol so you can spray it into tight spaces

Probably need to renew it once a year or so

I'm with the guys above who mention galvanic corrosion as being the major issue - after all we know that with a more noble metal like stainless fastened to a less noble metal like carbon steel - the problem is at the interface (weld or rivet)..

But Also as we know from plumbing pipes - if you make the connection gradual, for example by going from stainless to brass and THEN to carbon steel; the galvanic potential is less at each transition and will be less of a problem - though whether or not this is sufficient is beyond my skills to say.

Good idea though; and it is nice to see people willing to contribute ideas to start the discussion. I also like the ideas above of concentrating on eliminating any blind cavities in areas of steel panels exposed to salt spray.. that might alone just be enough with proper maintenance to turn a five year problem into a fifteen year problem..