This is the first step back in motor oil performance so if you want the very best it's going to be a sythetic oil.
Is it really necessary? Not really, but for me changing oil was part of my daily work for 19 years as a mechanic so I'm not real big on changing our oil, that's why I use sythetic in our 88' Mazda 626 turbo and 86' Mazda pickup and change it religiously every 10,000 miles.
Last I heard, Corvettes, Vipers, Porsches and Audis come with sythetic oil in them, the recommended interval for the Porsche Boxter is 15,000 miles and the Audi is 10,000 miles.
In my experiance sythetic is a must for turbos to prevent coking of the turbo oil drain hose and the only cars that needed their oil changed every 3000 miles were the air-cooled VWs because they had no oil filter, only a screen.
Best wishes, Craig