I recently checked my MC yellow coolant pH (which was changed ~2yrs/20K miles ago). I got a pH reading of ~7.3 which seems very low. I also checked the pH of new concentrated yellow antifreeze straight from the jug, and it had a pH reading of ~7.5. According to the MSDS it should be 8.7 to 9.2. I used an electronic pH tester that I have used before for water, not sure if it is accurate for coolant, or maybe it really is 7.5. I will try with test strips next time, confused by these readings.