yes, which is what it does as std. The valve is there so as not pressurise the system on on boost., and draws vapour in at idle straight into the inlet - this is a legal emissions requirement. What the used to do on the race 3i's which aren't allowed seperators, is block the metering inlet, and run the rocker outlet into a plastic bottle, but obv dont seal the pipe. Depending on how heavy the engine breathes, you empty the bottle of oil every so often. Of course, best thing is to get an oil seperator.