Alex Marks Killingworth, Connecticut - 2004 Jeep Liberty
In very cold weather her car sings, "Whooooooh," when she accelerates. It changes pitch when she takes her foot off the accelerator, and goes away when she's not moving. Tom and Ray think it is almost certainly the differential. She can change the fluid and if that doesn't help, ask her mechanic if there's been a technical bulletin on this problem. If that doesn't help, she can always turn up the radio.