whining noise coming from engine compartment
 

Recently purchased a 2007 S80 V8 AWD (yesterday 071810). During causal driving the "low oil level" message appeared. Checked the oil and it was a quart low. Added oil and car ran fine. Got home and a few hours later went to check oil (just in case) and there was this whining coming from the engine compartment. No air was blowing into the cabin and the engine was hot. Pulled the car out of the garage, once shut off the whining stopped. Opened hood and left it that way, still no whining sound. Shut the hood and the whining started again. Started car, parked in the garage, and no whining. It appears to be coming from behind the engine near the drivers side. Please help. Should I bring it back (I have five days to return car without penalty). Called dealer where I purchased, and I will be bringing it to my local Volvo dealer, they will be paying and repair costs, and for a loaner.

It could be the dryer fan for the climate control (there is a more precise name) which is perfectly normal. The fans also probably will not run with the car off and the hood open as a safety precaution. I doubt it's anything major.

Even so, as a 2007, unless it has high mileage, it should be still under warranty anyway.