I noticed as my wife was driving our '04 XC90 5 cyl. turbo (231K miles) away (250 miles each way to Maine) this morning that there was a whining sound at idle. It seemed to disappear with acceleration. I had just added a little oil to top it up, and an oil change was done about 150p0 miles ago. 5W-30 synthetic every 5K miles. She arrived in Maine OK and said the car drove OK, but she noted that the noise was still there. I did a quick search and see that the issue may be something to do with the breather box. Can she safely drive the car home tomorrow, assuming this is the problem? Also, is this a necessary repair? The car runs well (except for this new whine), but the body is rusting and won't pass inspection. I can continue to drive it, and I would spend a couple hundred to keep it going, but as it's probably on last legs, I'd like to save money where I can.