So if the recommend interval for an oil change is 5000 miles (8000 kms) based on regular (not synthetic) 5W20 or 0W20, and assuming you follow this recommendation what are the benefits to using synthetic (at a higher cost)?

Most of the reasons I've come across thus far for using synthetic has been that you can extend the recommended interval. But if you change every 5000 miles this argument is thrown out the window.

If you are using synthetic, why? If you're using regular, why?

Which weight (5W20 or 0W20) are you using? Why? Are your reasons based on the climate of where you live?

Is regular 5W20 and regular 0W20 priced differently? I was told by a local dealership that the 0W20 is more than the 5W20.