Engine coolant recommendations

I know the ELC(extended life coolant) is what the consensus is. If an engine has the original green coolant in it, should it be drained and replaced with ELC or can an additive, that actually works, be added? I’ve used the Napa(Wix) coolant treatment before, with the regular green, in the past but really not sure if it’s mitigating the potential of electrolysis.