E350 leaking oil from all 4 doors

Hello, tell more about the "dirty oil" -- when you touch it, is it literally oil? Or is it just dark moisture? There is no "oil" in the doors - so, it's a bit of a mystery how something could be an oil coming from your doors. I can imagine water from rain or moisture coming through the door and out the drain holes / vents -- which could be discolored due to inside the door dirt. Seek a shop near you to have it looked at -- maybe they'll have a better first hand eyes-on opinion. www.repairpal.com/repair-shops