On 03/08/2021 05:14 PM, bob prohaska wrote:

The old coolant (conventional green Prestone)

My '86 Toyota came with red coolant.

The original mix used distilled water, so total dissolved solids are
likely to be OK.

I used tap water when I replaced the red with green. From Santa Clarita
Water Co., ****tiest water in the Antelope Valley.

The major worry is the state of the corrosion inhibitors.

The Toyota's aluminum cylinder head apparently didn't appreciate having
green coolant, or the ****tiest tap water in the Antelope Valley.

Web searches for coolant testing found only specific gravity testers,
nothing about pH or other chemical tests.

I should have stuck with Toyota's red coolant.

Thanks for reading, and any stories!

Extreme engine overheating even while cruising in 5th on a level
freeway, on a cool night. Lots of aluminum was missing inside the head.
Couldn't find a replacement 22R head at the time, only 22RE heads, so
the shop TIG'd more metal in to fill the holes... allegedly. Whatever,
that fix didn't last. Struggled to reach 100K miles, and traded it in.