Black slug (Arion ater L.) is a common gastropod in forested areas of Sweden. In pre-industrial Swedish society and up to the beginning of the 20^th century, slugs were used as a regular or temporary source for grease to lubricate wooden axle-trees. Although the custom is mentioned in written records from the 18^th century, it is an otherwise almost undocumented practice. However, through an advertisement in a popular nationwide radio program, it was possible to record contemporary oral statements about this practice from a few decades ago. It seems to have been a widespread practice to substitute or improve the tar as cart grease with slugs in the older days. These animals, a freely available resource for everyone, were often gathered by children. The practice survived as long as the wooden carts and wagons were used, for example, in transporting hay. The study demonstrates that it is still possible to gather information about older practices in highly modernized societies, utilizing mass media as a way to reach informants.