My manual for the 99 r6 says to use 15w40, but I found some 0w40 synthetic I might wanna try out. I've been doing some research on oils and the first number really doesn't mean much as it's just how light the oil is. So in theory wouldn't a 0w40 oil protect more because it's lighter and will run through the engine easier on start up, at running temp it's all the same anyways at 40. I also hear people racing with 0w40 for increase hp and better mileage? Any thoughts?