For about 10k miles there was a bad smell from the engine compartment that was really only noticeable when opening the hood. Now that winter is here, the smell is nauseous in the car while idling/stopped with the heat running. The smell isn't present in the cockpit with the A/C running. After a short drive and shutting the car off, there are small amounts of whitish smoke coming from the driver's side exhaust manifold. It smells horrible, but I can't tell what it is (oil, coolant, exhaust, plastic, etc). While the car is running, it feels like there is the same amount of air coming out of each exhaust pipe. Coolant looks good and green and the levels aren't changing. The car isn't consuming any more oil than normal (I've had it for 92k miles and it's normally down a quart an oil change every time). I did have a fair amount of oil in a couple spark plug wells when I changed them a year ago. I'm thinking it could be a valve cover, but not sure? I've never changed the valve covers on this car and they could be stock with 180k miles. Any troubleshooting recommendations? Does this sound like a valve cover? It's not much smoke because I have to focus a light and really look to see it near the exhaust manifold with a light. It's a small amount of intermittent smoke, but occurs well after the car is off. My sense of smell isn't the best, but could burning oil make you nauseous (I thought it was just exhaust).