Car is a 2WD engine T34 siemens & harvey Gibbs chip, around 380bhp....

When i had the crap oil in 10/40 it was quiet as a mouse.

10/60 made the bottom end knock a bit but when reved was quiet. when the car warmed up it was fine.

Thinking of putting the 10/50 but its hard to get, i know someone who runs the silkolene engine treatment with good results, but don't fancy going down that route