Thanks for posting the image of the box instructions. Interesting the instructions just refer to "a few spots of oil" rather than any particular type.

Webley did amend the instructions for Mk 1 air pistols several times and it seems they did the same with the Mk 11 as well. That's the first example I have seen, where no particular type of oil is recommended and it stands to reason this would have been the earliest type.

On a slightly different note, you have a fine boxed Webley in the original box. Personally I would store/display the pistol with the original box rather than case it. My box is not quite as clean, so I feel somewhat envious of your very fortunate find!

Kind regards,

John