A note about distilled water: It's not as perfect as you think.

Yes, distilled water is pure. But it's also very chemically active and will tend to dissolve small quantities of metal (like aluminum) until an equilibrium is reached again. This is similar to "nature abhors a vacuum".

If your tap water has a large dissolved salt content (iron, magnesium, calcium, etc.) then use distilled water. If not, you are better using plain tap water which already has minute quantities of these in equilibrium, so your car's radiator and block don't become sacrificial.

Gerald C