Your owner's manual is the definitive source. Check it for the manufacturer's recommended oil weight and viscosity. If you don't have the manual, you can often find a digital copy online through Ford's website or a third-party parts website.
If the manual doesn't specify, 10W-30 is a common and versatile weight suitable for most conditions. In extremely hot climates, you might consider 20W-40, and in extremely cold climates, 5W-30 might be better. Always use an oil that meets or exceeds the specifications listed in your owner's manual. The manual will also specify the amount of oil your engine requires.
