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Old 01-24-2005, 10:23 AM
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Double Vanos Double Vanos is offline
Former ZHP pilot
Location: Austin, Tx
Join Date: Aug 2003
Posts: 884
Mein Auto: 2011 135i M Sport
Originally Posted by phlsteve
My dealer told me to simply add water. Since the concentration of the antifreeze from the factory protects it to crazy cold temps, a little water wouldn't dilute it too much. I ignored him, of course, and bought some good Prestone pre-mixed anti freeze. It was pricey, but worth the peace of mind. Ended up needing close to a half gallon of fluid.

Two dealers told me two different stories about why this happens, btw... One told me that the water in the antifreeze mixture is released a little bit at a time through a pressure release valve, causing the level to eventually drop. Another dealer told me that the water pump uses the antifreeze as lubricant, which eventually causes antifreeze loss. I don't believe either of these stories.

I've never before had a car that lost antifreeze (but all my past cars have been acuras, so of course not). As far as I knew, the antifreeze overflow tank is what deals with the fluid expansion. And I can tell you for sure that water, mixed with antifreeze or not, is a horrible lubricant, so I don't buy the water pump story either.

I'd love to know the real reason why this happens.

Yeah i called my service advisor this morning and he told me to just add a little water too. He also said that sometime these cars use a little coolant, especially the M3s he commented. So i went home and poured about 2/3 of quart of filter water in the coolant and the measuring stick rose to normal level. I think it wasnt a big deal and the light hasnt lit up again for now. I'll keep you guys posted.

My advisor said if it happens again to bring the car in and have it check out for a leak.
2011 135i M-sport ,6 speed, coral red, HK and ipod.
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