Before we can tackle what's new in synthetic motor oil technology, we should first make sure that we know what synthetic oils are. Mineral or conventional motor oils come from the ground, like the stuff that bubbles up in oil fields from Texas to Saudi Arabia. On the other hand, synthetic oils are man-made. Each company has a proprietary process for creating these oils that they're not keen to disclose.
If there were two puddles of clean engine oil on the floor, one puddle of mineral oil and one puddle of synthetic, it would be almost impossible to tell them apart. As ExxonMobil technical advisor Kevin Chinn quipped during a phone interview, "You'd slip on both of them." If two vehicles at 10,000 miles (16,093 kilometres past their last oil change were drained, though, the differences between the vehicle using mineral motor oil and the one using synthetic oil would be apparent: The mineral oil would be noticeably thicker.
Synthetic oils have been around for a while; Amoco sold one as early as 1929. During World War II, the Germans advanced synthetic oil technology when Allied forces strangled the country's oil supply. In the 1950's and 1960's, synthetic oil took off to meet the high-performance needs of fighter jets. Then, just as the fuel crisis of the 1970's took hold, Mobil1 synthetic oils that promised to increase fuel economy hit the passenger car market.
Despite the boost provided by the last fuel crisis, it took some time for synthetic motor oils to gain traction in the automotive market. The turning point came when auto manufacturers started to understand the benefits of synthetics -- such as fewer emissions and longer stretches between oil changes -- and recommended their use in newly built cars.
source: howstuffworks, wiki