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BMW coolant freeze point question
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11-30-2012, 06:39 AM | #1 |
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BMW coolant freeze point question
Hi guys,
I have some OE BMW coolant around and it says on the bottle that a 50:50 mixture will give you a -40*C freeze point, so i decided to test it out. I poured in a small recipient equal amounts of antifreeze and water and then tested the mixture. It said -18*C! I repeated the process, put same amount of antifreeze, but half the amount of water - and it reads -25*C! I don't understand, what's wrong?! How do i get it to read below -30*C? I used the same tester to test a fresh mixture of antifreeze on another car (Peugeot 207) and it reads precisely -37*C, as it should. I tested the bmw antifreeze alone and the tester goes off the scale, so it's concentrated, not pre-diluted. Any thoughts?
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BMW 320 dA LCI, BMW PPK - 197HP, 2010, sapphire black, steptronic
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11-30-2012, 06:41 AM | #2 |
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if you are using an old ball tester it is calibrated only for ethylene glycol type coolants. I don't know what the BMW coolant is but it may be propylene glycol, OAT, etc.
The tester works by reading the specific gravity (density) of the coolant/water mixture and it is ASSuming that you are using a mixture of EG and clean water - but the SG vs. freezing point graph will look different for different types of coolants. |
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11-30-2012, 06:51 AM | #3 |
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Here is the label on the BMW antifreeze and a picture of my tester. Antifreeze has ethylene-glycol and the tester says it's good for Ethylene-glycol.
Any other thoughts? winter is coming and i'm not comfortable with ~ -18*C that it's indicated with the current antifreeze, as temps may go below that.
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Last edited by EQUANT; 11-30-2012 at 11:40 AM.. |
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11-30-2012, 08:48 PM | #4 |
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I was under the impression that the anti freeze bought from BMW was straight antifreeze and had to be mixed with water to get 50/50. If you go to pep boys and look and anti freeze you'll see some bottles marked 50/50. We buy it by the 55 gallon drum so I'm use to adding water myself
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11-30-2012, 10:36 PM | #5 |
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Maybe times have changed, but a 50:50 mix is good to -34F, not C. And if you go beyond 70% antifreeze, you actually reduce the anti-freeze and anti-boil. Who the heck knows, I was always better at physics than chemistry.
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12-01-2012, 03:51 AM | #6 |
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This antifreeze has to be mixed with water, 50:50, as specified on the bottle. The weird thing is that 50:50 mixture only has a ~ -18*C freeze point, which is not enough.
@John - you are right. As i said, in the Peugeot they put pre-diluted Peugeot antifreeze and measured it with the same tester and the result was: ~ -37*C (-34*F -ish). I don't know how to get the BMW antifreeze to the same point. I will probably go to BMW and ask them to check the coolant freeze point and replace it, if necessary (although it had just been replaced at a local indy)
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