How can sawdust help you to sell cars, daddy? asked Matilda. I don't understand
"That's because you're a stupid little girl, her father said. He turned to his son. "I'm always glad to buy a car with an old gearbox, one that makes a terrible noise. I get it cheap. Then I mix a little sawdust with the oil in the gearbox and it goes beautifully - for a day or two.