I have a 2005 CTS with 38,000 miles on it. I've noticed in the last month or so that if my car sits out in the cold (less than 10 degrees or so) for a few hours, I will get a high pitched howling/whining noise at approximately 40mph. The noise seems to be coming from the back half of the car but it is hard to tell. The noise will go away at less than 35 or more than 45mph and will also go away after driving for 10 mins or so.

I don't believe it is the engine. If I'm hearing the noise, shift to neutral and rev the engine, the noise does not increase. It seems to corresepond with the rotation of the tires/drive train.

I've had the rear seal recall done. They looked and said they didn't see anything but it wasn't making the noise then. My only option is to leave the car with the dealer overnight and hope it would happen the following morning. I'm concerned because as the weather gets warmer the noise will probably go away until next year and by then I may be out of warranty.

Anyone ever heard of such a thing?

 

My car makes the same type of noise, I will bring it to the dealer to check the wheel bearings. I changed the differential oil and it did not change anything. If anyone else knows of this type of cold weather only problem please respond with a solution. Thanks