personaly when i ran 15/50 mine it ran crap when cold it was horribly noisey untill warmed up. the recomended oil for turbo cvh is 5/40 whic is what i use and mine is perfect from cold right up to when hot. hot idle is about 2bar or just under. 15/50 mobil 1 motor sport is more of a track day oil when the car is getting some serious abuse.