Synthetic oil has 3 main advantages:
Superior engine protection especially in severe conditions as in extreme heat in extreme cold. The oil flows thru the small areas of the engine better.
Synthetic oil has longer replacement intervals which means less time spent in the repair shop which makes it more convenient for the customer. However it is very important level is checked or every 1000 miles!!!
Price per mile is better with a synthetic oil then a standard oil. If the average cost for an oil change is $30 and you get 3000 miles for it, it cost $90 for every 9000 miles. With a synthetic oil you usually get six months or 10,000 miles which means you get an extra 1,000 miles for the same price.