Do you mix fuel for 4 cycle engines?

Mostly no, oil for lubrication is within a separate sump that is filled and changed separately. The exception is the Stihl 4-Mix engine which does use mixed fuel just as a two-stroke would. It traps oil in the bottom end of the engine to lubricate the bearings and uses the oil within the mist of the intake charge to lubricate the upper end and valve train.