I have just had a vaccum pump, rocker gasket and 2 plunger seals fitted to my BMW 318i MSPORT from a BMW specialist becuase i could smell a burning smell coming through my AC vents, after having this work done im only getting a light smell when i pull up at junctions or when i get out of the car around the wheel arches. Could this be due to excess oil that has spilled out onto the exhuast and engine before getting the work done?