When my engine warms up, I smell oil and when I put the windows down a little to get fresh air, the smell comes in more. I can't find any leaks. The car only has 34K miles.
oil smell on 2007 Volvo S40
It could be the valve cover gasket, but you will have to look again at the engine closely with a mirror and small flash light if the leak is not obvious. To find a difficult oil leak a garage may put a florescent dye in the oil, let the engine run and then look for the leak using a black light that intensifies the stain left by the dye if there is a leak.