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Old 19th December 2023, 03:24 PM
Saff Saff is offline
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Default Antifreeze Protection

Hi all. I've been measuring my coolant antifreeze protection level using a refractometer and found that my car's (presumably G12) coolant protects down to -16 degree C. Is that low enough? Granted I live in the rather sheltered North West of England and wouldn't expect temperatures to get as low as that but I was wondering what everyone's thoughts were. I also tested Mrs. Saff's Mercedes coolant and that was ok to lower than -40 degree C.

Any opinions folks?
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Old 19th December 2023, 06:14 PM
ainarssems ainarssems is offline
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-16C is probably low enough for England, but is it 25/75 or almost neat antifreeze 95/5 as both would be around -16C?

I would guess it's more likely to be 25/75 but it's possible that somebody filled it up with pure concentrate thinking it's ready mixed. Another thing to keep in mind that it's not just freezing temperature that you need to think about. Antifreeze also contains corrosion inhibitors, conditioners for rubber like hoses and seals and likely other additives, antioxidants to prolong antifreeze life. Normally you would use about 40-50% antifreeze and rest water. If you have smaller proportion it could affect other properties and reduce life.
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Old 19th December 2023, 10:50 PM
Saff Saff is offline
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Hi and thanks for the response. I can't say for sure which it would be other than the refractometer reading which I suspect bases it's findings on the specific gravity of the coolant. I assume that the higher the SG the higher the protection. I'm also quite happy to be corrected here. The service manual says the coolant is 'for life' so maybe the system has been broken into for reasons I'm not aware of. I'm tempted to have the system flushed and refilled. Food for thought anyway.
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