Hi.  There is a thread on here about this already but the answer wasn't really clear.  The handbook says 4.1 ltrs with oil filter and 4.0 without.  Two oil changes ago, the garage put 4.6 ltrs (with new filter) in as per some Ford listings but the the dipstick was always way over the full mark.  I change oil at half of its interval usually and last change I did without changing the filter with 4.0 ltrs and the dipstick mark was exactly correct.  So, how can a new and empty oil filter change with 4.6 ltrs be too much and a no change of filter with 4.0 be exactly right given that the book shows only 0.1 ltr difference between filter change and no filter change - surely the filter capacity exceeds 0.1 ltr?   Is it me or am I just thick?  Thanks.  Also, what is the 'fox' reference in the engine spec?

You're thinking of the oil filter as though it's just a hollow canister. It's not. There's only a 0.1 litre difference because the canister is packed with filtering material and a means of holding it in place. 

I would go by the handbook and your visual confirmation of the dipstick level being correct after filling with 4.0 litres. The fact that a previous oil change (4.6 l) sent the level too high on the dipstick should tell you something. 

Fox is just a Ford engine name for the 1.0 naturally aspirated engine (no turbo). The more common turbo version is the Ecoboost engine.