Atomised Oil is in the engine compartment

1961 GM car and the engine compartment has real light covering (film) of oil on firewall, inside fender, ect. Also the car smells of oil when put in the garage after driving it. It also runs rough at a idle seams to be ok at speeds. Any help or ideas would be welcome.

Multiple posts for the same car are not necessary, see my post in the Cadillac thread.