It's Italian, so maybe olive oil?
You will probably need to take it apart and see what's up. Sounds like the original grease/oil has frozen things, like on the Agfa folders.
If you can just get the elements out, you could soak the lens in the highest proof alcohol you could find. That's how I unstuck my Agfa cameras. On one that I couldn't get apart, I soaked the whole lens and shutter assy. It worked after a couple of days of soaking in a big coffee cup.
But you need the high proof stuff, the usual rubbing alcohol in stores is generally too low on the proof.