G12 Test: Your Ultimate Guide

Hello everyone,

Perhaps someone can help me and has relevant experience.
Since the end of 1996, the VAG group has used red G12 as antifreeze. I received several pieces of information stating that G12 cannot be tested using a refractometer, but only with an optical tester (e.g., Hazet). Does anyone have experience with conversion tables for converting old antifreeze to G12, or know of a source for an inexpensive G12 tester? The Hazet one is quite expensive.

Thank you for any response.

Jürgen (G4 AHF / Passat AFN)

Hello Jürgen,

"In my A3, the coolant initially installed was G12. A standard density measurement indicates freeze protection down to -35°C."
The display shows temperatures down to -40°C. It actually seems quite plausible.
Who uses an optical component for measurement, and is there a switch to select the appropriate setting depending on the antifreeze type?

Best regards, Rainer.

Hi,
Well, I can only agree with Rainer on that.
A few weeks ago, I had to replace the entire coolant system in my G3 AFN because the radiator was defective.
The calculation of the frost protection and the measurement using a cheap device from a hardware store only showed a deviation of 5°C.
Calculated: -35°C
Measured: -30°C
The deviation could even be explained by the fact that a small amount of old coolant was still present in the engine block .
'Please correct me if I have any inaccuracies.'