I have worked on all my cars and never heard anything like this. When i am rel;easing the clutch into any gear it sounds like there is cheap metal clinging around. at first i thought it was the little metal thing on the brakes that warns you when they are low cause it really sounds like cheap tinfoilish metal but it is extremely annoying. Im taking the car into nissan for the 30k service i never did and i have 43k on the car. so i will inform them of this i have the 100k warranty so i hope they cover it. Also has anyone noticed a difference when they get the differential and tranny fluids switched out?