Need to put more Engine coolant in my car

i suggest reading the recommendations on the engine coolant container because coolant contains rust-retardant chemicals not in water.

The proper term is Anti-Freeze/ Coolant. This stuff does both jobs. In the Summer it keeps your car from overheating. In the Winter it keeps your car from freezing up. It should be completely changed about twice a year. Change it once in the Autumn and again in the Spring. You should use a 50/50 mixture of water and Anti-Freeze/ Coolant all year around. You should NEVER ADD JUST WATER TO THE SYSTEM EXCEPT IN AN EMERGENCY. Adding just water to the system merely dilutes the protection that you have, resulting in more trouble than you need.