Ha ha ha.

Both viscosities are the same price and same brand. One is thinner than the other. In my car with a B18C7, it makes a HUGE difference. I can honestly say at least 1/2 second, if not 1 second at Wakefield. Would be more noticable at a drag strip I reakon. have tried a few different viscosities in my Dad's euro, and sister's Civic and the difference is barely noticable.

yes and I know removing mass from rotating assembly etc will make more of a difference, but in terms on engine oil... viscocities make a world of difference.

Just curious, what testing have you done on oils yourself?