Rear main seal leak

[BlackoutSteve]

The seal might be fine.. Often two dabs of RTV is forgotten to be added between the rear main cap and block -between the seal and the pan gasket (both sides).

One Band-aid fix would be to run your PVC valve as normal but not to use a breather on the other valve cover. This will create a vacuum in the crankcase that will suck oil in instead of allow it to drip out.

[bc69]

No it wasn't the installation. I though maybe after first time.
But after the attention to detail 2nd time I ruled that out.
The material the 2912 is made of is a better quality and the lip is stiffer.
I also don't like band aids in situations as this especially.
If a low vac sb can run without special attention  with  no leak then this L48
should. GM was able to do. It boils down in my opinion again to quality of materials.