There seems to be some myths/confusion about distilled water vs tap water. Distilled water, used by itself in a cast iron motor, will cause rust/corrosion just as quickly as tap water will if used by itself in the XJ cooling system. There's no rust preventative in distilled water just as there's none in tap water. Water by itself, of any kind, will quickly cause rust/corrosion in the cooling system......u must use a proper mix of antifreeze/coolant and any water, that is drinkable, to prevent rust/corrosion in the cooling system. If distilled water was required, seems like it would so state that on the Prestone Antifreeze/Coolant jug.....but it doesn't.

 

You're good to go until the next failure. Sleep well.............

 

Yea, agreed^, I've never used anything but what came out of the hose. Idk if some might have a PH issue. My water here is on the alkaline side, no trouble in decades. That said, what, a buck a gallon for distilled...a bargain at twice the price!

 

I used distilled water because my owner's manual said to use distilled water. I needed to get some for my iron anyway. At this point, I don't see what difference it makes since the PO most likely used a hose to replenish the tank for the last 23 years.

 

I clicked on the link to your photonet page. Nice stuff.

 

My point is, the motor is not doomed if distilled water is not used as long as the proper mix of antifreeze/coolant and water (drinkable) IS used and maintained. Is distilled water the purist.....yes, is it's use (with antifreeze/coolant) mandatory.....no.