well...PRE-cum comes out on its own. There really no wya to control it i know off...though usually it comes out in droplets, and if you 'explode' persay, its real cum. Precum is a little more watery than real cum,, witch is thicker like. You have no muscle contorl that can prevent precum, liek you can stop yourself from cumming for a little bit.
Life and Limb, Heart and soul, for you, I would risk them all.