GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 1997 🢒 Park Avenue 🢒 Engine 🢒 Engine Cooling 🢒 Coolant Concentration Testing

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

Coolant Pressure/Temperature Chart
Object Number: 108063 Size: LF
(1)Radiator Cap Blow-Off Pressure (Check Cap with BT-6225)
(2)Lb/Sq In
(3)kPa
(4)Hydrometer Reading of Coolant
(5)Light Off: Coolant Boiling
(6)Light On: Coolant Boiling

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 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 J 23688 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 .

    • Before each use, swing the plastic cover at the slanted end of J 26568 or J 23688 exposing the measuring window and the bottom of the plastic cover.
    • graph
         Wipe dry with a tissue or a clean soft cloth.
    • Close the plastic cover.

Testing Coolant Concentration

Tools Required

J 26568 or J 23688

Do not remove the clear plastic pump from J 26568 or J 23688 .

  1. Release the tip of the pump from J 26568 or J 23688 .
  2. Insert the tip of the pump into the radiator filler neck.

    3. Make sure the tip of the pump is below the level of the coolant.

  3. Press and release the bulb to get a sample.
  4. Insert the tip of the pump into the cover plate opening.
  5. Press the bulb and allow a few drops to fall onto the measuring surface.

    6. Do not open the plastic cover when taking a reading because water evaporation can change the readings.

  6. Point J 26568 or J 23688 toward any light and look into the eyepiece.
    7. • The coolant protection reading is at the point where the dividing line between light and dark crosses the scale (antifreeze protection is the scale on the right).

    Coolant Pressure/Temperature Chart
    Object Number: 108063 Size: LF
    (1)Radiator Cap Blow-Off Pressure (Check Cap with BT-6225)
    (2)Lb/Sq In
    (3)kPa
    (4)Hydrometer Reading of Coolant
    (5)Light Off: Coolant Boiling
    (6)Light On: Coolant Boiling
    • The temperature scale is reversed from a standard thermometer scale.
    • Below zero readings are on the upper half of the scale.
    • If the readings are not clear, the measuring surface was not cleaned and dried properly. Wipe dry and take a new test.