Smell of burnt oil through AC vents

2003 Mazda Protege5
Anyone know why I'm getting the smell of burned oil through my AC Vents? This is the second time this happens. After driving for a while the smell will go away, assuming wherever the leak may be just burns put. Any pointers on where to look would be appreciated. I have 03' MP5.
2003 P5
Give your engine/trans a good look over with a strong light. Check closely around the manifolds. You should get underneath too.


lolmsp lolms3
I agree with what Saudade said. If you find any leak residue, spray some brake cleaner on it and wipe it off really good then drive your car around. Next time you do the same checks it'll help you pinpoint where the leak is coming from. If necessary, they sell a dye to add to your oil that glows with a UV light. I haven't had to resort to that method but it sounds pretty efficient.