Quote:

water sitting out eventually becomes acidic.
co2 gets absorbed and it becomes carbonic acid.

so if the cap was off, or not sealed, the ph will be pretty low like you found.
also your meter/whatever might be a bit off.



Yeah but I JUST opened the bottle of Prestone and read it to 9pH...

My meter is calibrated with the included solution. I will redo the initialization of the meter in the morning to be sure but I don't think its to blame. When I checked it 3 months ago when this was just a TO DO on my list...my pH was 7.2 and I had 0.04v of charge in the coolant

Family owned 1969 Charger R/T DualQuad 440/727/GVO/3.55s