Be aware that using distilled water without Redline Water Wetter, or with other brand water additives, can cause problems with aluminum radiators, heat exchangers and blocks.
I had a severe build up of pressure, as have others, when I just used straight distilled water.
It turns out hte distilled water has no minerals, etc in it and tries to draw it out of the aluminum..Preesure builds up enough to cause even the tightest systems to leak, resulting in blown hoses, etc.
I have no experience with cars, but can state with certainty and first hand experience that in turbo Hayabusas this is a legitimate concern. I only use tap water now with Redline Water Wetter, and with a very expensive engine and turbo system at risk, have not had a problem with corrosion or pressure buildup.
Walt