[marksandygill]

Okay daft question maybe, have had a 17 plate 240i since Feb with 16k on the clock, now on 21k

Drove for 5 hours in rubbish traffic (32mph ave speed!) and then a couple of shorter journeys.

Next morning the coolant low warning came on so I topped it up with about 300ml and it’s been fine since.

My question is, as I’ve only ever had new BMWs for 9 months at a time, is this normal? Obviously if it does it again soon I’ll get it checked, but is it something I should be doing every 6 months or so anyway?

Oh, no signs of a leak under the car!😀

[freakystyly]

Missing coolant is accepted as normal for some reason. Just buy a jug of coolant and distilled water and live with the random loss. Replacing the reservoir caps may or may not help. It's good practice to check the levels at least on every oil change before the car asks. Welcome to the missing coolant club

[mecheng77]

No coolant loss here on N55, I’ve heard it’s the reservoir cap on B58

[freakystyly]

Originally Posted by mecheng77

No coolant loss here on N55, I’ve heard it’s the reservoir cap on B58

Correct, seems to be a B58 thing (maybe also 4 cyl variant?).

I've replaced the caps last spring and had to add ~1/3 of a standard water bottle (160ml, 6 oz?) of coolant to get it back to max over 8 or 9 months. So it mostly solved the problem but not fully.

[Kernel Kurtz]

Both my previous N55s and my B58 have required a small amount of coolant top up now and then (perhaps a couple hundred millilitres per year). Seems to be perfectly normal on these cars.