Synthetic oils have been used for a long time in military vehicles and fighter planes and before being released to the mainstream was used by airlines who continue to use them. The reason these organizations use synthetic oil is because it is designed for all weather conditions and does not break down easily. Synthetic oils also contain more engine protecting additives allowing you to go longer between oil changes as well.
This concept alone is a good reason for using synthetic oil. Even though synthetics cost up to four times as much as conventional oil the benefit is that you don’t have to change your oil every 3,000 miles as recommended for traditional oils and may be able to go as long as 7,000 miles. This doesn’t mean that you don’t pop the hood and check the oil and other items every 3,000 miles, just that you should not have to replace it that often.
For most people these days synthetic oil should be considered. It is recommended even more so for extreme driving which is stated as short driving of two to twenty miles which is tough on your vehicle and will cause a faster breakdown of the conventional oil.
With conventional oil impurities are just the nature of the beast and it is almost impossible to remove them while synthetics contain almost none. This fact is one of the reasons you can go longer between oil changes with synthetic oils.
You have to be careful in making changes on older cars as the switching to synthetic could cause oil leaks due to their not interacting with seals and gaskets in the same way as conventional oils.