wow guys..I too have been hearing this on my car since 122k. I bought the car at 122k and changed the timing belt and water pump because the owners neglected the car. I took it to a friend mechanic and he told he's hearing funning noise from the enigne due to old oil running in engine for a long time, and he said to change my oil often, which I change at 2500. The car makes a funny grinding, knocking noise around 1.5k-2.5rpm and I've been wanting to do a valve job. I have always thought that my engine was worn out because of negligience in changing oil but it seems there are other ppl with this "problem"