I wouldn't use straight tap water to flush. You will never get all the water out. The amount of rusting my be minimal but I've always used distilled.

 

The 4.0L cooling system isn't a Class 1 clean room... you realize the overflow tank is open to the atmosphere and the cooling system basically inhales dust, right?

 

I would use any water you can find. Once you add coolant back in- it contains inhibitors and additives- and will make the system completely fresh after a couple minutes.

 

quener is correct, distilled water is the right thing to use. Only need one of the 2.5 gallon jugs from the grocery store, just a couple of dollars and worth it. Yes distilled water picks up impurities and goes bad eventually, but tap water starts bad and has all the hard water junk in it from the get go. You can flush with tap but when you have all the old junk out, last fill should use distilled water.

 

He was talking about using distilled for flushing, not for the final fill. Distilled should obviously be used for the final till.

 

I flush and refill with holy water only.. Never have I had any possession issues with my radiator.

 

I flush with coca-cola and fill with flat beer.
Next time I might try that holy roller stuff. DemonsBeGone.
Now how do I get the yellow color?

 

I create my own "Holy Water" several times a day, can save you guys some money on it if you wish to fill with it

 

Yellow coolant is not compatible with green coolant!!!