lucky22
Yes. The mix in a radiator should be 50% water and 50% anti-freeze. If you just need to add, Use water one time and Anti-freeze next time.

campmano
mix it 50 50 antifreeze to water, or by the premix. this way you know you will not have too much water content to coolant, in case of cold weather.

Jay P
Yes. The mix should be around 50/50 in the cooling system already but it doesn't matter too much if you take it 60/40 water to antifreeze ( unless you live in an area that sees temperature dips to -30 or so ). Adding straight water ( distilled water is best ) to top up the fluid level is fine.

bproduct69
Yes, it should be mixed with water. 50-50 is usually good but check your owners manual.

stargazer
You could if you don't use too much....otherwise..you're just deluting to effectiveness of the coolant. Antifreeze is usually sold in two forms...straight..and a 50/50 mix. The straight antifreeze is usually mixed 1/1..that is..1 gallon of coolant to 1 gallon of water. The 50/50 mix...is already premeasured to just pour in right from the jug... so.. I would really stress...don't use too much water...if you are just using a little?...ok...but..if you plan on filling half the radiator with water...you're in for some overheating problems that will cost you more money than you planned on.

biff
Yes you may add water. It will weaken anti freeze so make sure it doesnt freeze up!!

terrellfastball
You can, but it dilutes the antifreeze's properties. You can do as suggested, water now, antifreeze next time, or take the easier solution. Most of the antifreeze you buy at the big blue box or local parts house is already premixed 50/50, just add.

George S
Yes you can put water in your Car radiator but don't do it if the radiator is hot ,Put yes you should have 50%water and 50% antifreeze but if you add water use a old antifreeze Jug that way you not just adding water.