I don't think that is your answer. From what I understand, if enough mayo builds up inside the CCV diaphragms it can cause intake vacuum to be diverted to the dipstick tube drain hose. That condition will suck oil directly out of the dipstick tube.
- First, you should probably make sure the dipstick tube is not clogged with gunk.
- Then maybe you should be checking for vacuum on the dipstick tube drain hose? There should not be any. Disconnect the hose and connect to a vacuum gauge. Cap off the nipple on the dipstick tube.