Ford recomend 5w-30 semi or full synthetic for the Zetec engines because anything thicker can cause the some valves to stick, poor engineering by ford there in my opinion. The truth is they recomend this to cover their back, we tend to suggest that people stick to it however there are many Zetecs out there running around on Castrol 10w-60 for some reason (trendy I guess).
The 0w-40 you are running on at the moment is overkill but should not cause any problems for you.
Next oil change look for an oil that meets the Ford WSS-M2C913-A/B spec and you will be fine, most are semi synthetic but Total does do a full synthetic one.