I came across this video
http://www.youtube.com/watch?v=4G-PgNielZY and it sort of sounds like my car sometimes when I FIRST start it up from a cold start but not quite that loud. It kinda scares me, so if I cut the car off and start it back up, it's not there anymore. Side note, I also have a dented oil pan. I have another one, but I haven't put it on yet.
Is partial rod knock possible? Wouldn't it sound that way all the time, and especially if you revved?