If anyone has really figured out why some engines corrode and others don’t, we haven’t been favored with the explanation. We’re told by engine shops we periodically contact that engine corrosion has reached epidemic proportions and that more owners than ever who should have reusable cams and cylinders at overhaul are seeing them trashed by rust instead.

Tanis Engine Dehydrator blows dry air into the oil filler tube and extracts it from the oil breather.

This trend has ignited a dual-pronged interest in engine corrosion control. One is aimed at improved oils and additives—we reported on that topic in the April 2006 issue of The Aviation Consumer—and the other is what’s best defined as active corrosion prevention by gadgets called aerators or engine dehydrators. Theoretically, these work by pumping…