Oil covers the surface of the water in the siphon and toilet with a film. And since the oil does not dry and does not dissolve in water, the film accordingly prevents the water from evaporating. And that means the smell can’t get through in such conditions. The oil film prevents bacteria from developing.
Moreover, the holding power of the oil is retained for about a month or even a month and a half, then the film begins to disintegrate. But I didn’t check it for such a long period of time, this is according to the plumber.
Upon returning home, it is enough to wash everything with your usual cleaning product or warm soapy water.
I usually leave home for 2 days and still fill up the oil. Because I learned from experience. I ventilated that fetid smell for more than one hour. Even a powerful draft could not drive him out of the apartment for a long time. I don’t want history to repeat itself.