Ya I've got a picture of an oiled K&N filter that came in my last powerstroke from the previous dumbas, err.. owner. Oiled K&N + turbodiesel= nono. What happens is all the dust and dirt literally form sludge-cake on the filter. The longer you let it go for, the thicker and heavier the sludge-cake becomes.

I'm very impressed with your scangauge data though showing the difference in mpg. And very surprised it was that noticeable. I appreciate your input!