is it bad to mix coolant and water? it says not to on the can of antifreeze, but there was a bit of water in the radiator.

 

Is it premixed stuff in a bottle, the 50:50 stuff to top off with? Don't dilute further. If the motor was full of just water, drain it and add plain antifreeze (there will be a lot of it left in the motor). If you're just a little low and it's the regular 50:50 mix, it's fine to top off.

 

It will just throw off your mixture of propylene glycol to water ratio. You can test your level of protection with a coolant tester kit

 

Or you can drain your radiator from the drain plug at bottom and drain your block from the coolant jacket drain plug. Add brand new Honda/Acura pre-mixed coolant

 

plain and simple, your motor will not be negatively affected by a 48/52 mixture. 50/50 is best, but thats almost never reached perfectly.

 

Only dilute antifreeze with distilled water. Tap water has corrosive minerals.