in my car manual, the maker recommends Fully Synthetic 0W-20 and Conventional 5W-20 & 5W-30 for my turbo engine. But, the dealer sells only100% synthetic oil. Some people define “100% synthetic” as motor oil made exclusively from Group IV polyalphaolefin (PAO) base oils. In contrast, they define “full synthetic” as an oil made from Group III base oils. They assert that Group III base oils are highly processed conventional base oils due to the manufacturing process used to make them. Hence Group III base oils aren’t truly “synthetic.”
After a high speed drive it is always a good idea to let the car idle for a minute before turning off the engine. In doing so you let the turbo to spin down to a much slower RPM under lubrication. There are also after market electric turbo oilers and they will run a small electric oil pump to continue to lube the turbo for a few minutes after the engine is shut off. Although the electric turbo oiler requires quite a bit of installation and most drivers might not be able to do-it-yourself it saves you time from sitting in the car waiting for the one or two minutes idling but most importantly it saves your turbo from spinning dry (no oil) after the engine is shut off. The turbo oiler can also pre-lube the turbo before you start the engine.