well im ing Nulon 10-40 fully synthetic and im glad i used it..... i won 5 litres last year at extreme horsepower for winning the 6 cylinder naturally aspirated dyno class.
i had heaps of people tell me not to use fully synthetic in a non turbo...but she has due for an oil change back in feb i think it was, and the oil is still see through now, starting to get a little bit dark. however if i had been using the :"normal" oil it would be as black as black by now and id probably be thinking of doing another oil chnge before it gets to the stage where it is so thin that it makes my oil pressure drop.
but yeah thats my 2 cents on what i use, im really happy with it and the car loves it......so im gonna keep using it