Mechanical Magic wrote:
...how it works. It's just a pinhole. Air pressure enters the chamber, and
when air pressure falls, it pushes oil into the air line. ...

OK, that explains it: if the pinhole is down (immersed in oil), then
mucho oil will be pushed into the line.

I would just oil the hose (as others have said). ...

It does seem to be the unanimous view & I'll go with it.

Thanks to all,
Bob