I have a 2010 Subaru Outback which takes Subaru blue long life coolant. Pep Boys has a gallon undiluted for about $15.00. On a Subaru forum was advised to use the premixed long life blue because it has deionized water, not distilled. Apparently deionized water is not easy nor economical to purchase. Does anyone have opinions on the superiority of deionized water vs distilled? Frankly I have used tap water for most of the last 35 years with no apparent problem. I have read city water reports and fail to understand how a few parts per million can affect cooling system??? In the last year or two have switched to distilled water for rinses and flushes because of low cost. Is deionized water worth the extra expense of a pre-diluted blue coolant?
Scott
Scott