Quite a few years back, I had a Ford truck with an oil bath (I was 14 and driving with a hardship license). Didn't really know squat about vehicles so I didn't check any under-hood stuff out. My dad checked it out, I bought it and about three days later I was giving it hell out in a field when it starting boiling smoke out the pipes. I was sure I screwed it up so I headed back to town and it cleared up almost immediately. I got to my grandparents house to explain how I was 'just driving down the road' when it started smoking. My grandpa opened the hood and showed me the air cleaner and told me it wouldn't have swallowed any oil if I hadn't been 'acting up'!!
That's the only oil-bath I've had. My '39 arrived sans-air cleaner and my '67 has a paper element.