Quote Originally Posted by TFOGGER View Post
The zinc is needed to prevent gear teeth from galling in bikes that use a shared oil supply between engine and transmission (most modern bikes). Diesel oils work well in most applications, but have reduced shear resistance at very high rpm compared to engineered motorcycle specific oils, leading to more rapid viscosity loss at elevated rpm (over 10000 or so).
For something like a TW200 or XT350, would you recommend just sticking with motorcycle specific oils?