Don't be surprised if a new fan clutch does not lower coolant temp. gauge readings. My 126 has a new radiator, head gasket, hoses, coolant exp. tank, exp. tank pressure cap, 50/50 MB coolant/H2O. Just replaced fan clutch with OEM item. Fan blade was spinning for quite awhile after shutting engine off. Blade now stops right after shutting engine off; however, my temps still go from 87C to 100C if I get stuck on the freeway if there's been an accident.
I've also experimented with 40/60 & 30/70 concentrations and have used Wetter Water. Temp. gauge readings never change.
126 owners manual indicates that rising temps are quite normal, so I'm going to put this fluctuating temp. issue to sleep.