A possible cause is the oil breather tower.  The vent is tied into the
intake. If it is bad, then there is nothing to restrict the vent and oil
vapor can be sucked into the intake (the vent is before the throttle body and
IS a source for intake air), increasing oil consumption.

Rockers increase the airflow and with a bad breather, could increase oil
consumption.
Plus if you have a stock restrictive air filter, this could cause an increase
also, because the oil breather vent provides an easier path for the intake
air.

I am wanting to put in a system similar to the Berg oil capture system, but
at a smaller cost, plus valves cover vents to better control the oil vapor.

Robert