[morzh]

Things I would not use on any metal (unless this is my purpose to use exactly those) are acids and alkali. This is regarding the vinegar.
Aluminum gets a bit dissolved in acids, and when storing acid foods it is not recommended storing them in aluminum containers unless one has a serious lack of it in his blood and wants to replenish it.
And vinegar is stronger by itself than when it is diluted in food.

However small part of the cap's plates it will dissolve, this may change the capacitance.
Of course some caps have steel plates. Still not sure it is good.

Solvents / fuels are neutral.

And, of course, don't use them at home,, use them outside, away from the house, and ultrasonic is not needed - just use a brush.


PS> Having said this, since my cap in my Philco was simply dirty but not grimy, I successfully washed it in my dishwasher. It was not aluminum so it did not darken.