I need help on what oil to use in my 2002 yz426f. It seems to have a notchy shift feeling and it seems to find neutral when im riding and dont want it to and to be hard to find neutral when i want to put it in nuetral. Any ideas of what oil and i need to know how much to put in it. I am thinking about shell rotella b/c i have heard good things about it. But how much and what viscosity should i get?