Agree with johnsey, they aren't picky at all. The roller bearing bottom end doesn't give a hoot about viscosity so just about anything is fine there, even thin sheared down high mile oil. The top end has big wide bucket followrs on the cam lobes and fairly light springs, doesn't require big additive levels so wooring about zddp or whattever is a moot point IMO. I've had a 600, a tengai, and still own a 92 650 and have put lots of different oils in them, no real winners or losers. Think mine has 10w30 troparctic in it at this moment. They're not bikes they are appliances, LOL. There's some stuff online about adding more than the sight glass level, don't agree. Been there done that, they'll windage and blow off the extra oil if your riding at higher rpms. Proved it (to myself anyway) on trips where we quit topping it and found it stopped using.