Alright I have always used Magnetec 10w-40 without any problem. Changed oil at 5000km intervals and by then the oil was finished, Very black and thicker than it should be.
I have just changed to Softec 5w-30, thought I would take REZLO's advice and give it a bash, and I am very impressed. The oil heats up faster and stays at 90-100degrees no matter what. On the trip back from joburg, a 32degree day the oil temp never went above 101degrees, even with a run to 240km/h. There is absolutely no tappet noise in the morning and when you blip the throttle when the car is cold the motor sounds good.
Magnetec is a good oil but it doesnt come close to this, WOW.