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I've bought an antifreeze tester yesterday, and the scale on the floater is divided as follows:

  • the upper half is for methanol-based antifreeze, the lower half is for the ethylene glycol-based one (so far it is clear which one I have to look for, since my anti-freeze is ethylene glycol-based)

  • however both halves are divided again into two separate sections (the upper one is green, the lower one is white), and the numbering is not continuous, but restarts from low negative in the white sections. (EDIT: and it covers again the same range as the green one!)

See illustration and picture at the bottom to make it more clear.

Question: how do I know if I have to check for the upper, or lower section of the ethylene-glycol scale? (Also, implicit question: why are there two different scales at all for one kind of material?)

Remark: I tried to measure my (ethylene-glycol-based) antifreeze, and it showed -17 degrees in the white section, but I don't know if the measurement was "right" or not.

Illustration

    +--+
    |  |
    |  |
    |  |
    +--+ -40 degrees C    ---+
    |  |                     |
    +--+ -34 degrees C       |
    |  |                     |
    +--+ -29 degrees C       |
    |  |                     |  green
    +--+ -23 degrees C       |
    |  |                     |
    +--+ -17 degrees C       |
    |  |                     |
    +--+ -12 degrees C    ---+
    +--+ -34 degrees C    ---+
    |  |                     |
    +--+ -29 degrees C       |
    |  |                     |
    +--+ -23 degrees C       |
    |  |                     |  white
    +--+ -17 degrees C       |
    |  |                     |
    +--+ -12 degrees C    ---+ ------------------ METHANOL
    +--+ -12 degrees C    ---+
    |  |                     |
    +--+ -17 degrees C       |
    |  |                     |
    +--+ -23 degrees C       |
    |  |                     |  green
    +--+ -29 degrees C       |
    |  |                     |
    +--+ -34 degrees C    ---+
    +--+ -12 degrees C    ---+
    |  |                     |
    +--+ -17 degrees C       |
    |  |                     |
    +--+ -23 degrees C       |
    |  |                     |  white
    +--+ -29 degrees C       |
    |  |                     |
    +--+ -34 degrees C    ---+ ------------------ ETH GLYCOL
   /    \
  |      |
  |      |
  |      |
  |      |
  |      |
  |******|
  |******|
  |******|
  \______/

Picture

scales on the floater of the antifreeze tester

0

The instructions that came with the tester will confirm, but the sections to the scales will be concentration dependent.

ie the green section will be for a concentration above 20% and the white below that, 20% given as an example...

  • Unfortunately, no instructions came with the tester. I do not really understand the answer either: What happens if in one car I read -17 on the white scale, and in another car I read -17 on the green one (the scales cover the same range!)? Does this mean, that in the first car the concentration of eth. glycol was e.g. 16% and in the second it was e.g. 24%, but both achieved -17 degrees freezing point? How is that possible? – Attilio Dec 2 '18 at 10:57
  • You bought it yesterday and have lost the instructions? Or they were missing... If they were missing, go back to the shop and get them replaced. Or, buy another... with instructions... – Solar Mike Dec 2 '18 at 11:01
  • I wonder if the two scales in each section are for testing at different antifreeze temperatures (i.e. a hot or cold engine) - but you would need to know what the hot temperature was supposed to be to get accurate results. – alephzero Dec 2 '18 at 13:09
  • @SolarMike "going back to the shop" might be hard, if the OP bought it from here: picclick.com/… (and note it says "vintage" in the description!) – alephzero Dec 2 '18 at 13:14
  • 1
    @alephzero well, I would prepare a couple of antifreeze concentrations and test it to find out exactly what it does... – Solar Mike Dec 2 '18 at 14:30

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