My view is that most rigging failures, for most properly built sailboats, isn't related to corrosion; rather it's a function of fatigue or other stress failures that have little to do with that.

The build-up of coatings in a heat exchanger of an engine which is in "fresh water" is a little worse -- but still not that much different over a period of time. The outside of an ignored engine can turn "rusty" in fresh or salt water. I think that the inside of the engine really doesn't know or care whether it's in Chicago or Newport. ;^)