Depending on manufacturer specifications, synthetic motor oil changes can last up to 15,000 miles. Synthetic oil is specifically manufactured to resist breakdown and sludge buildup that leads to the need for more frequent oil changes that are still necessary for cars using conventional motor oil.
Synthetic oils are engineered to perform well under very high temperatures, including hot weather and the high temperatures created by turbocharged engines. They are also designed to perform well in cold weather and have been modified to remove impurities that lead to oil breakdown.