A Ford Mondeo diesel turbo's oil requirement depends on the specific year and engine model. Ford has used various engines in the Mondeo over the years.
You absolutely must check your owner's manual. It will specify the exact type and grade of oil recommended for your particular Mondeo.
The manual will list the correct viscosity grade (e.g., 5W-30, 0W-40) and likely specify an oil meeting a certain Ford specification (e.g., WSS-M2C913-A, WSS-M2C913-B, WSS-M2C937-A). Using the incorrect oil can severely damage your engine.