Olive oil as a conservant.

[Matchlock]

Originally Posted by broadaxe

Olive oil hardens over the years, creates a thick layer that 'freezes' moving parts.

That's absolutely right; olive oil is definitely nor recommended for mechanical parts!!! It will freeze them.
The old-time recipe for them was either stone or bone oil. I too prefer Ballistol (a Lower Bavarian poduct, btw ...) for mechanics - and only for them.

Sorry for not mentioning this earlier but I understood the discussion was about outer surfaces.

Best,
Michael