Just spoke to ford about this they said if it has a reservoir it will be under the rear arch the same side as the fuel flap the dpf will have small pipe around it if it has a reservoir, they need topping up at 37,500 miles and ford charge about £150 to do this, some of the newer cars the dpf is coated for life but they seem to think thats a 2008 would be the old system.

Hope this helps.
Dan