mineral

Okay, I'm about to do my second oil change in my FS 650 and now I have a question; The manual tells me to put SYNTHETIC 10w-40 in it but the workshop that I bought the bike from tells me that I should run Belray 20w-50 MINERAL. What am I missing? The clutch shouldnt slip with synthetic right?

Not me, my 2011, fe390. Have bled clutch a few times, level keeps dropping. Is there an oring in bottom of slave that can be leaking. 40 hrs on bike. Ive used almost entire magura bottle in past two months.