Motorists occasionally pump gasoline into a diesel car by accident. The converse is almost impossible because diesel pumps have a large nozzle with a diameter of which does not fit the filler, and the nozzles are protected by a lock mechanism or a liftable flap. Diesel fuel in a gasoline engine—while creating large amounts of smoke—does not normally cause permanent damage if it is drained once the mistake is realized. However even a liter of petrol added to the tank of a modern diesel car can cause irreversible damage to the injection pump and other components through a lack of lubrication. In some cases, the car has to be scrapped because the cost of repairs exceeds its residual value. The issue is not clear-cut as older diesels using completely mechanical injection can tolerate some gasoline—which has historically been used to "thin" diesel fuel in winter.