Abstract: A device and method for unloading frozen or congealed crude oil, oil product, or chemical cargo from a railway or highway tank car. A brief heating step uses the high thermal conductivity of metal tank walls, and the low thermal conductivity of oil or chemical cargos, to thaw a relatively thin band of cargo adjacent to the longitudinal tank wall. This thin band of thawed liquid lubricates the remainder of the plug, which remains solid, so that the plug can be mechanically ejected into a receiving trough positioned at the same height as the emerging plug; this avoids the requirement of completely thawing the frozen cargo before it can be pumped out. A tank car is disclosed having at least one end wall that can be opened, allowing a frozen or congealed mass to be physically ejected from the tank as a solidified plug.