Okay guys I'll jump in this,
I live in Las Vegas and have for all my 50 years. The water here is high in alkline (very hard). Those chemicals that naturally occur in our water tend to come out of the water and bond to the internals of a cooling system. (If you've ever been to Lake Mead and seen the white ring around the lake you know what I mean) My brother has owned and operated a radiator shop here for years and recommended to me that I try distilled water in my 61 Corvette. The water seems to be especially active with aluminum radiators, and you don't take one of those apart and clean them. There is a definate reduction in deposits when distilled water is used in cooling systems in lieu of the stuff that comes out of our taps. Also don't use soft water instead. Most water softeners use salt to regenerate the core of the unit. This leaves a salt residue disolved in the water that will really cause problems in a cooling system. Real distilled water (not mineral water or even purified water) has all dissolved chemicals and minerals removed and is PH netural or close to it. Therefore it sould be much less likly to react with the materials that our cooling systems are made of. My own personal experience with this and that of my brother, has convinced me of this. By the way did you know that pure water cools much better than antifreeze?. I've seen lots of discussion about "Water Wetter" and the like lately, but one of the things we do here in the desert is reduce the amount of antifreeze in the summer to about 10%. You need some to resist rust and keep the pump lubed, but the increased about of water seems to move more heat out of the engine. Just remember to change back to a proper mix if you live in areas that freeze. Also keep an eye on the coolant for rust. If it starts to show up, you went too far. My conclusion and belief is that if you live in a part of the country that has lots of dissolved minerals and chemicals in the water, distilled water is far better for use in our cooling systems. It's cheap and I can't find and haven't seen evidence that it is harmful. I use it in my cars and have for years. mgg (Gold # 209)
[This message has been edited by Manny Gomez (edited 06-29-99).]