[capt_slow]

Originally Posted by Billfitz

It does, and corrosion can occur. If you don't see any change in color then a reasonable change interval is 6 years or 100,000 miles. If you don't want to fix what isn't broken, or fail to fix what is broken, get some coolant test strips. A lifetime supply will cost you less than $20.

Good advice. My DMM read 0.07V on my F31 at about 32k of factory coolant. Ordered some PH test strips too.

EDIT: I dont think the DMM is quite accurate, as it says there is enough voltage for corrosion to occur. But I just used the test strip and it says I'm ok on PH and glycol content. Ran the same test on a pH meter and it read out to 8.14.