Builder, yes I have heard that the oil can mess with oxygen sensors on late model vehicles.
Jerry, that is exactly what they are doing, larger pores w/ oil to trap small stuff. That's the only way it could work to increase air flow, as you noted. It's exactly like running an oil bath only not quite as messy. It's also fantastic where I'm at since I sometimes spend lots of time on gravel roads with fine dust. That oil catches more of it than a dry paper filter does. For that kind of application I highly recommend it. Now, if all a person is doing is tooling around in town then it's probably not worth it.
There is another aspect as well. They are durable filters that produce less waste. The K&N filter I have on my '71 was originally purchased over 10 years ago. It started out on my '63 C10 until that bit the dust and then it went on my '71 and is still filtering on just fine. In this throw-away society I prefer having things that will be around a long time.
