How to Test Antifreeze Freezing Point (-°C) | Car Coolant Tester, by ROKAJ on YouTube. 1 min 41 s.
- Video length
- 1 min 41 s
- Time to do it
- 10 minutes
- Difficulty
- Easy
- Steps
- 9
What you need
Steps
Park on level ground and let the engine cool completely, ideally overnight. The coolant level and the tester reading are only accurate when everything is cold.
Open the bonnet and find the coolant reservoir, usually a clear plastic tank with MIN and MAX marks. Do not touch the radiator or reservoir cap while the engine is warm.
Unscrew the reservoir cap slowly to release any pressure, then set it down on a clean rag.
Squeeze the rubber bulb of the tester, put the tube into the coolant and release the bulb to draw fluid up over the pointer.
Hold the tester level at eye level and read the number where the pointer sits. That figure is the freezing point of your coolant.
Use the right column on the scale for your coolant type. Scales usually have separate rows for ethylene glycol and propylene glycol coolants.
Compare the reading with the coldest temperature your area reaches in winter. You want protection at least 10°C below that figure.
If protection is too weak, top up with pre-mixed coolant or a 50/50 mix of coolant and water, then test again.
Return or dispose of the sample properly, rinse the tester with clean water, and refit the reservoir cap firmly.
Tips and common mistakes
Never open the cap on a hot engine, because scalding coolant can spray out under pressure.
Retest after any top-up, since even a little water changes the freezing point.
If the coolant looks rusty, milky or sludgy, have the cooling system checked instead of just topping it up.
Tap the tester gently if the pointer sticks so you get a true reading.
Questions
What freezing point should my coolant have?
Most cars run a 50/50 coolant and water mix that protects to around -37°C. Aim for protection at least 10°C below the coldest temperature you expect.
Can I just add water when the level is low?
Only in an emergency. Plain water raises the freezing point and weakens corrosion protection, so use pre-mixed coolant for top-ups.
How often should I test the antifreeze?
Once a year before winter, and any time you top up or notice the level dropping.
This guide was drafted from the video's details and general task knowledge. It has not been checked against the full video. Check the video and relevant product instructions before following a procedure. Report a correction.
