VW 1302 Heater

Some anxiety comes out in my mind on heating system of VW Beetle. The duct connecting fun shroud and heat exchanger was remove from the begining, though I imagined the reason was the space occupation by big bulk Yoke compressor, trial application in success of the duct there proved the imagination was not correct. Applicable but intentionally removed!
Engine oil pilling for long period of time on the center coupling of the outer case of heat exchanger on the left side bank head cover portion and removed heater duct wanna say something?
Long term oil pilling from the head cover gasket would invade into the heat exchanger,be burnt on the exhaust pipe and unbearably terrible stench irritate cabin filling with smoke? They are no unnatural story?