Coolant testing Issues - Refractometer Recommendations
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Instructor
Joined: Aug 2007
Posts: 121
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From: Saline MI
Coolant testing Issues - Refractometer Recommendations
I tested my dexcool coolant with a new Prestone Ethylene Glycol coolant tester (Plastic baster type with red plastic pointer. Package specifies it works with all Ethylene Glycol including Dexcool) and it only shows protection down to -10. Since our temperatures can dip below this, I purchased a fresh gal of concentrated GM Dexcool to redo the system. To assure my new tester was giving me accurate readings before I drained the system, I mixed up a 10oz batch of 50/50 Dexcool with distilled water and shook it up extremely well. To my surprise the new Prestone testor only shows the mixture to be good to about -8. The GM Dexcool shows a 50/50 solution should be good to -34. Tried another Prestone testor (same style) from a friend on the 50/50 test batch and the reading still were only -7.
I plan to do a compete flush in the spring but need to assure that I have adequate freeze protection over the next couple months.
I have read several articles indicating the specific gravity testors are very inaccurate and they recommend using a refractometer. Anyone else having problems with Prestone style testors?
Any recommendations where to purchase a good but reasonably priced automatic temperature adjusting Refractometer for coolant analysis.
I plan to do a compete flush in the spring but need to assure that I have adequate freeze protection over the next couple months.
I have read several articles indicating the specific gravity testors are very inaccurate and they recommend using a refractometer. Anyone else having problems with Prestone style testors?
Any recommendations where to purchase a good but reasonably priced automatic temperature adjusting Refractometer for coolant analysis.
Tech Contributor
Joined: Oct 1999
Posts: 41,058
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From: Charlotte, NC (formerly Endicott, NY)
I have a couple of different testers supposedly good for testing Dexcool and they give me different answers. I stopped using them and just make sure I mix the proper quantities together to get the 50/50 mix. I doubt the antifreeze makers could lie about the percentages for all of these years and all of the antifreeze sold without being caught. I know the automakers would be really upset if they got caught up in warranty issues because of freeze up.
Bill
Bill
Burning Brakes
Joined: Feb 2005
Posts: 1,190
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From: Fayetteville AR
I sure the Prestone tester is fine. What you should have done is pour the Dexcool at 100% strength so it can dilute with what you had already to bring it down close to the -34. You may have to drain the rad a little and add 1/2 gal of 100% to get it down to the -34. I would drive the car for 15 to 20 min so it can mix up the entire system so you know the block is protected.
Safety Car
Joined: Nov 2000
Posts: 4,419
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From: Arroyo Grande CA
Have you tried these? Dex-Cool has different results than conventional anti-freeze.
http://www.acustrip.com/specs/2-wayafauto.html
http://www.acustrip.com/specs/2-wayafauto.html
Tech Contributor
Joined: May 2008
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From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
Rinse it out
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From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
I tested my dexcool coolant with a new Prestone Ethylene Glycol coolant tester (Plastic baster type with red plastic pointer. Package specifies it works with all Ethylene Glycol including Dexcool) and it only shows protection down to -10. Since our temperatures can dip below this, I purchased a fresh gal of concentrated GM Dexcool to redo the system. To assure my new tester was giving me accurate readings before I drained the system, I mixed up a 10oz batch of 50/50 Dexcool with distilled water and shook it up extremely well. To my surprise the new Prestone testor only shows the mixture to be good to about -8. The GM Dexcool shows a 50/50 solution should be good to -34. Tried another Prestone testor (same style) from a friend on the 50/50 test batch and the reading still were only -7.
I plan to do a compete flush in the spring but need to assure that I have adequate freeze protection over the next couple months.
I have read several articles indicating the specific gravity testors are very inaccurate and they recommend using a refractometer. Anyone else having problems with Prestone style testors?
Any recommendations where to purchase a good but reasonably priced automatic temperature adjusting Refractometer for coolant analysis.
I plan to do a compete flush in the spring but need to assure that I have adequate freeze protection over the next couple months.
I have read several articles indicating the specific gravity testors are very inaccurate and they recommend using a refractometer. Anyone else having problems with Prestone style testors?
Any recommendations where to purchase a good but reasonably priced automatic temperature adjusting Refractometer for coolant analysis.
Griot's Garage sells one, but as usual all he is doing is taking an item available elsewhere in the market-place, marking it up in price and re-selling it via his catalog. In my searching, I found the exact unit he is marking up for approx. $10 to $15 cheaper.
I plan on getting one. Not sure when just yet, but I will eventually do it.
HTH
BTW, Dex is propylene glycol not ethylene. If your Prestone tester says it's good for all ethylene fluids "including Dex-Cool", I'm thinking
Last edited by LoneStarFRC; Feb 2, 2009 at 08:54 AM.
Tech Contributor
Joined: May 2008
Posts: 3,100
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From: Somers, CT and Clermont, FL
St. Jude Donor '09-'10-'11-'12-'13-'14-'15-'16
Thread Starter
Instructor
Joined: Aug 2007
Posts: 121
Likes: 1
From: Saline MI
Update:
So I went to a local radiator shop today that had a professional specific gravity testor and both samples tested -20 to -30. Not sure why the Prestone baster style did not work very well but I am now satisfied that I have adequate freeze protection for the next few months and plan to do a thorough flush this spring.
Thankyou all for your input!
BTW - The GM Dexcool label indicates it is a silicate free ethylene glycol coolant so ideally the Prestone tester should have worked.
So I went to a local radiator shop today that had a professional specific gravity testor and both samples tested -20 to -30. Not sure why the Prestone baster style did not work very well but I am now satisfied that I have adequate freeze protection for the next few months and plan to do a thorough flush this spring.
Thankyou all for your input!
BTW - The GM Dexcool label indicates it is a silicate free ethylene glycol coolant so ideally the Prestone tester should have worked.
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