I have tried many times and always failed, but I've never asked either.
I opened a vintage set and the tires have leaked plasticizer. I don't mind
throwing away the tires, but a number of pieces in the bags with them are slick.
With baby wipes and isopropyl I have always succeeded in making them not oily
or sticky, but I've never lost the smudgy sheen. Does anyone have a method
for doing this well?