pH of some coolants

[Snagglefoot]

Got myself an electronic pH meter and comes with packaged powder to mix up solutions for calibration. I decide to check out two common coolants, check their pH in of their concentrated solution then mix them 50/50 with water. I didn’t have distilled water so I used bottled drinking water with pH close to 7 and well water that went through a softener, cartridges and a reverse osmosis cartridge. It had a lower pH of about 5.7.

The photos show water and the concentrate from the jug, with the jug shown, then the pH meter in each sample, then the two mixed together and the sample split in two with the pH meter in one of the cups. First I’ll use the samples with the bottled water with Prestone with Cor-Guard. The water had a pH of 6.76, the concentrated Prestone had a pH of 8.44 and a 50/50 mixture had a pH of 7.97.

 

[kschachn]

pH of plain water is pretty meaningless. But on those coolants that would be the buffered pH, how about titrating it to get the buffering capacity? That's what we need to know

 

[Snagglefoot]

Now here are the same tests with Prestone Dex-Cool. Again, the bottle water was 6.88, the Preston Dex-cool was 8.66 and the 50/50 water and coolant mixture was 8.35

 

[Grand cherokee hemi]

I'm surprised at the ph level of the prestone concentrate... I thought it would be higher

 

[Snagglefoot]

pH of plain water is pretty meaningless. But on those coolants that would be the buffered pH, how about titrating it to get the buffering capacity? That's what we need to know

Have at it.

 

[Snagglefoot]

Using the slightly acid well water that went through a softener, then filters and a reverse osmosis cartridge, the pH was 5.75. The resulting pH of the mixed 50/50 water/ coolant was 7.93 for the Prestone with Cor-Guard and 8.30 for the for the Prestone Dexcool. You are welcome to make your own conclusions. Just having fun with my new toy.

 

[mfewtrail]

Now here are the same tests with Prestone Dex-Cool. Again, the bottle water was 6.88, the Preston Dex-cool was 8.66 and the 50/50 water and coolant mixture was 8.35

View attachment 41936View attachment 41937View attachment 41938View attachment 41939

Prestone's Dexcool concentrate is listed at a pH of 8.7 on the sds, so that meter appears to be accurate enough: https://www.whatsinproducts.com/types/type_detail/1/12662/standard/span style="color:

Search out the other SDS' and most should list pH.

 

[Jetronic]

Thanks for sharing. This shows to me that the ph is easily disturbed and care shoiuld be taken what water is used to dilute the coolant.

 

[kschachn]

Thanks for sharing. This shows to me that the ph is easily disturbed and care shoiuld be taken what water is used to dilute the coolant.

Absolutely not. Coolant is highly buffered and the differences seen are irrelevant. It’s almost impossible to obtain a correct pH reading for plain water given the extremely low H+ concentration. It’s also difficult to measure the pH of a non-aqueous substance such as ethylene glycol. The measurement of the mixture is likely the truest reading.

There is no way plain water will significantly alter the pH of a buffered coolant, that’s the point. But it’s also why I mentioned titrating the mixture since then you know the acid absorbing capability. As is the pH readings so far don’t really tell you much at all.

 

[Snagglefoot]

The measurement of the pH of the bottled water was 6.76 which matches that quite closely to 7. We proved it’s not vinegar. The pH of the Prestone Dex Cool was measured as 8.66 close to the data sheet of 8.7. It was hard to measure that? I think not.

It was true the difference in effect of 5.7 pH water and 6.76 pH bottled water had on the coolant was very small. Do different coolants have different buffering ability? Yes, more than likely.

 

[doitmyself]

What I see: The Dexcool started out higher pH and remained higher at 50/50. Vice versa for the Corgard.
The buffered pH difference using well vs. bottled water was insignificant: 7.9x ph for Corgard and 8.3x pH for Dexcool.

You "might" use up some of the buffering capacity with anything other than distilled or D.I water.

What kschachn is saying is that we do not know the capacity of the pH "sponge" with either coolant. Like oil TBN, we don't know how well either coolant will be at the end of several years use with the cooling system shedding metal ions. I.E., after 5 years, the Dexcool might be 7.6 pH and the Corgard might be 7.8 pH.......we don't know.

How does one insert spread sheets here???

 

[Snagglefoot]

View attachment 42040

What I see: The Dexcool started out higher pH and remained higher at 50/50. Vice versa for the Corgard.
The buffered pH difference using well vs. bottled water was insignificant: 7.9x ph for Corgard and 8.3x pH for Dexcool.

You "might" use up some of the buffering capacity with anything other than distilled or D.I water.

What kschachn is saying is that we do not know the capacity of the pH "sponge" with either coolant. Like oil TBN, we don't know how well either coolant will be at the end of several years use with the cooling system shedding metal ions. I.E., after 5 years, the Dexcool might be 7.6 pH and the Corgard might be 7.8 pH.......we don't know.

How does one insert spread sheets here???

Looks good except change the description. Bottled was 6.8. Well was 5.8. Rest is correct.

 

[doitmyself]

Sucks getting old! Fixed

 

[Leo99]

Do you still have the same samples? Measure them again today and see what you get. I'm curious if they vary from day to day.

 

[Snagglefoot]

Do you still have the same samples? Measure them again today and see what you get. I'm curious if they vary from day to day.

Sorry, they’re gone, but I can probably mixed up another Prestone Cor Guard. I have room in the expansion jug. Stay tuned.

 

[Leo99]

Sorry, they’re gone, but I can probably mixed up another Prestone Cor Guard. I have room in the expansion jug. Stay tuned.

Keep the samples a few days and retest. Rinse the meter between readings with water.

 

[Snagglefoot]

Keep the samples a few days and retest. Rinse the meter between readings with water.

Hey Leo. I made up a new sample and have it in one of my wife’s canning jars I expropriated. I’ll report back. The current pH of the 50/50 mixture is 8.08.

 

[Snagglefoot]

I believe the ph of the well water varies a bit because of the water softening cycle. Some CO2 is liberated to the water during the softening process and this varies depending on the regeneration cycle of the resin beads. The source of the CO2 is the high calcium in the water.

 

[kschachn]

If your water is changing the pH of the coolant to any meaningful degree then that’s the worst coolant one can imagine.

 

[Snagglefoot]

If your water is changing the pH of the coolant to any meaningful degree then that’s the worst coolant one can imagine.

Bring out your favourite. You can see it’s not much of a difference. This last test is for good old Leo.