Originally Posted by enrita
I'm referring to how on boost, blow by will be directed through the oil separators in the valve cover, through OP's BMS OCC and into the rear turbo intake tube. Oil is only passed through the six orifices in the head (one in each intake port) when the engine has manifold vacuum.
The two ways I can think of oil getting into the rear turbo intake tube are if oil is making it through the OCC when the intake manifold in under boost, or if oil is getting through the DVs when the throttle plate closes. If the oil was in the charge pipe, and was going through the DVs, it would be present in both intake tubes. If the oil was passing through the OCC, it would only be in the rear tube.
However, if oil is in the rear intake tube after passing through the OCC, it is probably making it's way into the charge piping via the rear compressor. "