you have to use the specific funnel to pour any liquids into the fuel tank or it will just be a waste - i too learnt the hard way.
petrol cars have a black funnel and diesels have a white/clear one. purchase from fords few a few quid!
they look like this:
Ford UK Part no.
if your car is a Petrol ask your local dealer parts desk for: FINIS1670446
if your car is a Diesel ask your local dealer parts desk for: FINIS1681668
from this thread: http://www.fordownersclub.com/forums/topic/34977-fuel-funnel/