Oil Filter Housing Gasket Potentially common leak on the X350s and only requires taking off 3 bolts to replace, my gasket was completely shrunken - noticeable difference from the new one and was causing a decent leak. You will have to top off as well of course. I managed to only have to add I believe 2-2.5 quarts to get back to level, much better than a full oil change as an Indy had quoted for and just having done one