The addition of the separator changed the vacuum.
Separators are the closest thing to snake
oil in the automotive industry. The
oil that is captured is miniscule and does not affect in any way the operation of the engine. It's built into the plan. If you're pulling a teaspoon of drainage every 1000 miles then the engine would have taken care of that just fine. That is the design of the PCV system from day 1.
Now, if you have a boatload of
oil in the separator you've got a bigger problem. The separator isn't going to fix it. It is an alert though, but then so is the smoke you're getting from the tailpipe.
The exception is the case where you track the car under varying angles from horizontal and it might capture a little more than normal. But even that isn't a problem. Consider it top oil.
When Shelby American added them for the early GT500s I knew their VP that brought it in and explained this. He said something like "we know, they are bling, but people want to buy them so we will sell them".
PS. You will NEVER need one on both sides. One side is vacuum and the other is exhaust. (I dont remember). Everyone always says one side has some and the other side has none. If that other side has some then you've blown your engine.