No, It should not suck any oil vapor from the valve cover other than a slight coating that will develop over time. There is a coalesing filter inside the valve cover and when it needs to be replaced, a message will tell you on your overhead console. This filter is monitored by a crankcase pressure sensor directly to the rear of the it. The filter is designed to keep crankcase pressure controlled without the risk of a runaway. So if the pressure difference is too much (like a clogged coalesing element) the route of oil vapor will be closed from the turbo to protect from a runaway but will cause crankcase pressure to rise and will set a code and possibly derate engine power.