What Synthetic oil weight is right for the 2004 4.6-liter SOHC V-8 GT Mustang?
The 2004 Mustang GT 4.6L SOHC V8's owner's manual will specify the recommended oil weight and type. However, 5W-20 is generally considered the recommended weight for that engine and year, especially if you're using synthetic oil. Always check your owner's manual for the manufacturer's explicit recommendation, as using the wrong weight can damage your engine.