which oil in 451 gasoline

Hello, the search tried but did not find the 451 petrol. So as the topic name already says, I want to know which oil comes in the Smart 42 451 year 07/08 and how much. I didn’t get smart from the Smart homepage. Is that true that you should put 0.5 liters of weninger in as smart says? If yes, why? and why should smart make false statements?