A cdr valve does for a diesel what a pcv valve does for a gasser. It removes vapors that cause pressure from the crankcase. It allows the oil to separate from the vapors and drop back to the intake. If one is plugged severly I could see it pushing oil out seals and gaskets but I couldn't see it causing oil consumption. That is normally caused by stuck or worn piston rings, or bad valve guides, but thats just my thoughts.