 Bought a new 2008 Sentra S back in Feb and have had an ongoing issue with the transmission. Any time I ease off the accelerator in 4th, 5th and 6th gear, I can hear a high pitched whining sound. Started noticing it before 1,000 miles and brought it to the dealership. They test drove the car and told me it was normal. The sound kept getting louder and the dealership agreed to replace the transmission at 2,500 miles. The sound was still their after the swap, just not as loud. 6,500 miles on the car now and whine is back. Nissan says it is normal once again and refuses requests for additional work on car.  