I noticed something else interesting earlier today while I was changing my oil and coolant. While I was sitting in the car waiting for the engine to warm up to bleed the cooling system with the front end still jacked up, I got bored and ran it through the gears. I noticed that the transmission whines somewhat while spinning the wheels, especially in 5th gear (presumably since the output side of the trans is spinning the fastest). But what's really odd is as soon as I push the clutch in, that whining noise goes away or at least gets quiet enough that I can't hear it over the engine/exhaust noise even though everything in the trans is still spinning. But as soon as I let the clutch out, the noise is back. That doesn't make any sense to me because everything in the trans is still spinning with the clutch pushed in until the wheels come to a stop. I'm not overly concerned about this, but I'm really curious why disengaging the clutch would make the trans so much quieter despite the fact that everything inside the trans is still spinning. Anyone have any ideas?