horn oil

This is pretty vague.

Miss Marple came to me with an Italian made pneumatic(???) horn that has a
little cap on top of the cannister that says 'oil'.

Would anyone know what I'm talking about and know what kind of oil and how
much goes in there?

Robert Duquette
Ottawa ON Canada
http://www3.sympatico.ca/robertduquette
RobertDuquette@Sympatico.ca
'65 RHD BRG AH Sprite
'67 RHD red MG Midget < aka: Miss Marple >

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///  (If they are dupes, this trailer may also catch them.)