Oil for protection. Wipe clean before use. Re oil afterwards

Personally, I don't bother, and have yet to have problems, but maybe my oily hands do the job anyway.

Howard

I would think it depends on how they are stored. My workshop is quite dry – it being dehumidified for a couple hours each night. While my machines and tooling are obviously oily from use (the machine wearing parts are kept lubricated), the ones that are not used often show no signs of degradation. i wipe the male morse taper with my hand before inserting it – to be sure no swarf is getting trapped – as a matter of habit. Every time I pick it up to fit it.

If your workshop suffers from any condensation there is no choice but to keep them well oiled, when not in use, I would have thought?

From the steel construction industry:

The corrosion of structural steel is an electrochemical process that requires the simultaneous presence of moisture and oxygen. In the absence of either, corrosion does not occur.

Martin C