Coolant Concentration Testing

Tools Required

^ J 23688 Coolant Tester (Fahrenheit Scale)
^ J 26568 Coolant Tester (Centigrade Scale)






Some coolant manufacturers mix other types of glycol into their coolant formulations. Propylene glycol is the most common new ingredient. A hydrometer does not always provide a correct measurement of freeze protection when anything other than ethylene glycol and water is being tested. The degree of inaccuracy varies depending on the proportion of other glycols present in the coolant.

All new GM vehicles are produced with coolant that can be accurately measured with a hydrometer; however, when the type and quality of coolant being measured is unknown, such as a customer vehicle that has accumulated mileage, the use of a refractometer is recommended.

Coolant testers J 26568 (Centigrade Scale) or J 23688 (Fahrenheit Scale) can be used to check the antifreeze protection of the coolant. Make sure the refractometer markings are correct. Unless J 26568 or J23688 has a provision for temperature correction, test the temperature at which J 26568 or J 23688 is calibrated. If the coolant is warmer or cooler, the reading may be incorrect. Follow the manufacturers' directions on using J 26568 or J 23688.

Clean

^ Before each use, swing back the plastic cover at the slanted end of the coolant tester, exposing the measuring window and the bottom of the plastic cover.
^ Wipe the measuring window dry with a tissue or a clean, soft cloth.
^ Close the plastic cover.