Thanks for posting a 1st gen valve cover. The Gen3 is vastly an improvement.
Slung oil is the issue combined with short driving periods where oil cannot get hot enough to steam out any moisture. The cooler oil gels and condenses inside the baffle area of the valve cover creating a high pressure situation internally which the vacuum can draw oil from.

If you have oil consumption issues, its best you minimally pull off the rear valve cover and clean out the baffle if you don't want to spend on a 3rd gen cover. I would be hesitant to just pour seafoam or any top end cleaner through the pcv area to clean the baffle, doing so my dislodge sludge into the head.

Comparative pics of 2nd and 3rd gen covers are on post #14