The smell is normal. In regards to the synthetic oil - the Mobil Lubrication Engineer explained to me that synthetic oil is NOT absolutely 100% synthetic. During the crude distallation process they capture some of the lighter gas/liquid from the very top of the column which is used in a chemical process to manufacture the synthetic stuff. The stuff coming off at the top of the column is the absolute BEST stuff from the crude. The lower quality stuff comes off at a lower section of the column - diesel fuel is above #6 fuel oil and gasoline is above both of these, etc. #6 or "bunker C" is probably the least refined stuff.