Roo - while I agree that acetone wouldn't be my choice of track cleaner either, I'm not clear on what your table sez in this regard. For something that winds up as a thin film on the rails, such as WD-40 or other oils, a low dielectric constant (I guess the preferred term is now relative permittivity - a 'trick' this old dog is gonna have trouble remembering) would be preferred - quite apart from whatever other properties a specific cleaner/solvent might have. But if the solvent, like gasoline (low dielectric constant in your table) or acetone (higher dielectric constant in your table) evaporates, then it seems to me the dielectric value is largely irrelevant, is it not(??).
More importantly from a safety point of view, the use of gasoline is a terrible idea as a solvent - especially when used in enclosed spaces that might have a source of flame or ignition (basement with a furnace or water heater...). Carbon tet - while not flammable - is a liver toxin and frankly, not something to mess with (when there are better, safer, alternatives). Both butyl and ethyl acetate, while in the middle of your table of dielectric constant values, are both flammable also. I think there is a very important distinction between what one might use as a solvent in a well-ventilated space - a garage workshop that isn't part of the house - and what one uses in a basement or living space trainroom.
