coolant = antifreeze

it does not help the efficiency of cooling system. WATER by itself cools better than water plus antifreeze. there are ingredients in coolant to prevent rusting though.

if you have a leak just replace with distilled water for now. don't worry about coolant until you have it fixed.

I don't run antifreeze/coolant in my vehicles since the weather here never go below freeze. just distilled water and water wetter.