Hello, fellow DIYers. I was checking all of my fluids the other night and I noticed my radiator fluid had a rust/mud color in it. I assume it isn't that bad because I could still see the green from the antifreeze/coolant (Compared to others I have seen where it is completely rust colored.) I was wondering if it was okay to flush it with city water from the faucet outside and then after flushing mix it with my new antifreeze/coolant. I have heard some people say you should only use distilled water and some people say that the city water was fine.

 

Depends on WHERE you live

If you can "taste" your city water then it will have minerals in it, and minerals are Salts

Distilled water means it has no minerals, its been boiled and the steam vapor captured and condensed back to pure H2O, distilled
Bottled water has minerals, they add minerals to some, lol

The minerals/salts in the water shortens the life of coolant's anti-corrosion additives, think Salted roads in winter and what it does to car bodies and frames, thats what happens inside the cooling system.
Simple as that, the more minerals there are the shorter the protection life of the coolant.
If you use distilled water you get the full 2 years of protection, or 5 years with HOAT based coolant

Filling the engine and driving it for a few days with city water(flushing it) won't hurt anything because you will be draining it out as much as possible and then refilling it

You have the facts so up to you on which way to go.

Flush out heater core in BOTH directions

 

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