Cooling system flush: distilled water how many times?

If you had a 1st gen with an unknown maintenance history, but no overt issues with the cooling system, how many times would you run distilled water through the system before adding fresh coolant?

 

None, if you are flushing just use hose water.

 

Though regular water was a no-no

 

If you are flushing it out at the end then why should it matter.

 

I've read that it introduces minerals that solidify over time. Not sure how true but it's what I've read.

 

There won't be any damage if you use it to flush and then fill with coolant and distilled water. I'm sure there are tons of people who use regular water and coolant with no issues.

 

I would say most of the damage comes from cars that sit a lot and also are never serviced or changed. Same with oil.

 

Best if you can find the block drain plug, flush and when adding coolant mix with distilled water only. Toyota or Pentosin red is usually 50/50 mix. I'd suggest a new thermostat if you are flushing. OEM only.

 

Fill with distilled water and drain 3 times usually yeilds clear water.
Add 1 gal Red full strength after last drain gives you 50/50 mix because a gal stays in block after draining radiator.