coolant

yes and it depends on how low temps get in your area or where you will be driving. generally 50/50 is the standard mix. if you buy coolant make sure you read label as they come pure and already 50/50 mixed. also mix ratios for temps will be on pure container instruct label

Coolant does not mean only for hot weathers, They have antifreeze properties that are important for winter, especially under freezing conditions.