[AlanAZ]

I've lost 1/4 of inch on the coolant gauge in the reservoir tank over 2 months and 1,500 mls (admittedly during summer in Arizona.) It's a 06 325i with 60,000 mls, and I don't know it's history of coolant loss since I bought it 3 months ago. Car runs fine, no coolant on the floor or in exhaust.

I've read here that some coolant loss is normal, still this loss seems high, 1.5 inches per year on the gauge if I extrapolate. What's the usual rate of loss? Any typical cause for a higher rate of loss?

I bought an fluorescent dye to add to the coolant to identify any seepage or weeping. Any issues with using this with BMW's coolant (it says not to use with GMs Dex-cool, no mention of BMW)?

Thanks.

[ctgazer]

my coolant was bone dry in 14 months...

[GMWNashville]

some is normal..its just the way it works in bmws..always use oem coolant and water..

[F32Fleet]

I doubt many people check this sort of thing since they lease. For example I checked the coolant of my car 27 months after buying and the coolant was at the 'low' mark. Turned out I had a leaking radiator (BMW POS plastic/metal radiators) which explained why when I first bought the car that I smelled antifreeze for about a month. The leak was soo small that it just vented small amounts of coolant in the form of steam so I would have never noticed.

[FCP Euro]

I lose about a 1/4 of an inch every 6 months or so. Mainly in the summer months.

[dgraham1023]

It is normal to have some coolant loss. Depends on your driving stlye, environment where you live. Coolant will dissipate, adding a cup to two cups of coolant every month or so is normal.