I noticed that my fiancees 300M has a very rapid soft tick only when its idling, or running at low rpm with not much pressure on the gas pedal. The only time I hear it is when were up next to sumthin. I tried an oil change 5W30 Castrol Edge to no avail. 87000 miles 3.5l ho. We were told a new belt was put on it when we bought it a year ago. 15K miles since. I lifted the hood and it sounded like the belt...but ive never heard it on any car before unless the oils gettin thin? Any ideas? Thanks for the help ahead of time.