i dont race stock so i cant tell you anything on that. i race open brushless. im running 30wt oil i nthe shocks, so i would think 30-40 would be fine. its a yokomo lcg, so chances are that it has stuff that is set for racing on it, so i wouldnt worry all that much about the shock pistons and stuff. worry more about grip, speed, handleing, etc. i dont mess with shock stuff other then oil weight and im fine with it. just my opinion though