Need some help please

[eicheldp]

In December, I took the Porsche out on one of the unusually warm days and I noticed a whine coming out of the engine compartment while the car was moving. I drove slowly and carefully until the car started to warm and as the warming increased the whine decreased. At normal operating temperature, the whine is barely distinguishable.

Car goes back into hibernation, a few days ago I take the Porsche back out and the same thing happens, except the outside temperature is above 75 F. I recently changed the belt in between these two drives, just because it needed it and I thought it might help.

The 2004 S is a tiptronic and I'm wondering if the fluid or filter needs to be changed in the transmission or if it might be the differential. The fluid is original and there is 28000 miles on the car.

Any advice is appreciated. If you have questions I'll try to answer them.