Mixing coolant ? N00b question.

[TTommy]

Hi all,

I have a E46 3 series, known for their cooling systems weaknesses..

My water pump went a few months back, so I had it all done and flushed/ refilled with coolant by a bmw specialist. He said to just check it when cold and if it needs a very small top up with water that will be fine. (Coolant by concentrate I guess?)

So anyway, I did that and thought nothing of it, literally must have put in 20-40ml.

Now, I checked it again and it's slightly low, (still within the min / max but closer to the min than it was 5000 miles ago.

Am I safe to be topping up minimal amounts with normal water ? I heard it can be bad to do this. But I suppose not if it's a concentrate in the system.

Or am I better off using coolant? Can you mix them as I don't know what went in. I do have some bmw stuff kicking around.

I just don't know the answer so thought I'd ask !

Thanks in advance guys!

[PaulKemp]

1 litre is ok but if you do this on a regular basis it means you have a leak and should take it back
I used to carry a couple of litres of premixed for top up on an old shed

[CrutyRammers]

Ideal would be to mix some up from concentrate and use that, but using a bit of water will be quite alright.

[Matt Seabrook]

Don't mix different types of anti freeze. If the garage used a BMW spec use the same.