It is common knowledge that distilled water is free of minerals that cause rust and corrosion. Why do the auto and truck manufacturers not put distilled water in the cooling systems from the factory and advise consumers to use only distilled when changing or flushing systems?
I wish I knew the answer to that! Generally it is recommended that one use distilled water for mixing with antifreeze or when doing flushes. However I don*t believe they use distilled water from the factory, and to be honest most dealers and shops I*ve ever worked at don*t either.
There are rust inhibitors in the coolant, and that helps. It*s important to do flushes either way even when using distilled water, so it somewhat becomes a wash.
〉 Answered on Feb 27th, 2009 by Bogi Lateiner, Owner and Technician at 180 Degrees Automotive