Turbated engines are not recommended to be muted immediately after stopping, as a oil-tanning oil may be formed on a hot turbine. In order for this to happen, it takes some time to let the engine work on idling speed so that the turbine is cold.
Volkswagen claims that the oil that is littered in the seventh generation Passat does not burn. However, the operating manual recommends that the engine be allowed to idle for a few minutes after active driving.
