Which Water for Cooling System?

[Dhos1]

I have always been told distilled

 

[~JM~]

Use DI H2O

Yes DI may attract some minerals from the coolant passages, but very limited as it reaches equilibrium quickly. May be somewhat beneficial if there is some accumulation. You might consider a DI flush & dump, then fill. I run DI, RMI & aluminum safe antifreeze. My engine short block is the least clean component in the system.

 

[xlr8ngn]

I don't mix, I just pick the color that tastes the best.