Hello everyone, I've got an '06 Cobalt with about 110,000 miles that has been relatively problem-free, until now. I hardly drive my car, but am diligent on regular oil changes and have been using Mobil 1 exclusively for years. Over the past few weeks I've noticed a stronger-than-normal exhaust gas smell coming through the vents during stops at red lights. I just explored further today and don't see any obvious leaks with the exhaust system, but when I took the oil cap off with the engine running at idle I could feel considerable pressure (and the exhaust smell) originating from the oil filler cap! I'm hesitant to take it into a shop and get raked over the coals for an engine rebuild. I don't hear anything abnormal, the oil looks great with no signs of antifreeze mixing in, and the coolant reservoir is also normal. I wonder if it's as simple as a bad PCV valve, but I know that's probably wishful thinking. Anyone had this happen yet, know what it is, or know of an "easy" fix? Thanks.