[rant]There is some rust on your spelling too, I think 😀 it is actually "aperture", and this is one of the most common misspelling of photographic terms on the various fora, so common that even magazines do that sometimes - I think knowing & using the proper spelling for the terms we use everyday for our jobs or passions would be a good thing to do, maybe even more important than de-rusting some aperture blades... 😀[/rant]
Sorry about the rant! About the OP's original questions, answers have already been provided to which I wouldn't be able to add anything out of my limited lens-de-rusting knowledge. 😀