[Rukka]

Just had the light come on for low coolant yesterday. Car has just done 7.5k miles.

Checked both reservoirs and the main engine one is just below minimum and the charge air one is on minimum.

I'm not overly worried as I know a lot of folk with the B58 have had the same thing at around the same mileage and it looks like there is some evaporation overtime (venting through cap). I really can't be arsed to book it in for a day either for them to tell me all is ok.

So I've picked up a bottle of anti-freeze from BMW parts today. 1.5L for £11 was not so bad but my question is..... do I add it neat or mix it?

Parts dude said mix it 50/50 but given water boils at 100 degrees and the glycol boils significantly higher (cant remember from memory how much higher) surely it's better to have less water and more anti-freeze?

Anyone know the mix ratio of the top of their heads to save me RTFM?

Thanks in advance.

[Sasquartch]

Glycol does boil at a higher temperature than water but water has a much higher SHC (specific heat capacity).

That means a litre of 50/50 coolant can carry a greater amount of heat energy from the block to the radiator than pure glycol

I would add at a 50/50 concentration as that is what the system is designed for.

[HighlandPete]

Don't forget you have a pressure cap, boiling point is elevated, so not an issue.

[Rukka]

Cheers guys. Had a little google about too and that seems to concur with the 50/50

HighlandPete - understand that but my thoughts were that if these B58's are losing coolant through evaporation (venting via the cap) then lowering the temperature of the coolant by increasing the anti-freeze/water ratio may help a little.

I know a couple of guys with heavily tuned motors that run pure glycol in them with no water.....

Was just a thought

[Grant_7]

I wonder when mine will need a top up? Will have to buy some antifreeze in prep...damn, was at the dealership earlier today <doh!>

[Rich9600]

Originally Posted by Grant_7

I wonder when mine will need a top up? Will have to buy some antifreeze in prep...damn, was at the dealership earlier today <doh!>

I'm in a similar boat. Though, I bought some when my wife 1.5i Mini (B38?) was low at about 7k miles. So, I'm pre-prepared...

It seems to be a 'B' Series feature...

[Daftasabrush]

Originally Posted by HighlandPete

Don't forget you have a pressure cap, boiling point is elevated, so not an issue.

Not a very good pressure cap

Mine's been sneakily topped up by my dealer but I've never had a warning about it.

Noticed it was low when the car was new but it never complained so I left it. I've got a bit of residue around the cap too. Now the coolant is much more full following its second service.

[Rukka]

Originally Posted by Daftasabrush

Not a very good pressure cap

Mine's been sneakily topped up by my dealer but I've never had a warning about it.

Noticed it was low when the car was new but it never complained so I left it. I've got a bit of residue around the cap too. Now the coolant is much more full following its second service.

Noticed a bit of residue round my cap so obvious it's been venting.

Read on another post (American) that they reckon the caps have a fault. Remains to be seen if it happens again.

[bimmer456]

Originally Posted by Rukka

Just had the light come on for low coolant yesterday. Car has just done 7.5k miles.

Checked both reservoirs and the main engine one is just below minimum and the charge air one is on minimum.

I'm not overly worried as I know a lot of folk with the B58 have had the same thing at around the same mileage and it looks like there is some evaporation overtime (venting through cap). I really can't be arsed to book it in for a day either for them to tell me all is ok.

So I've picked up a bottle of anti-freeze from BMW parts today. 1.5L for £11 was not so bad but my question is..... do I add it neat or mix it?

Parts dude said mix it 50/50 but given water boils at 100 degrees and the glycol boils significantly higher (cant remember from memory how much higher) surely it's better to have less water and more anti-freeze?

Anyone know the mix ratio of the top of their heads to save me RTFM?

Thanks in advance.

Bring to dealer. I had that happen at 8.2k miles. Common issue. They pressure tested and didn't find anything but topped off coolant no charge. Even got a loaner for a few hours! A 320i. After I got back into my 340i sport line I was like this is way better than that car lol. Yes it may be evaporating through the cap there may be a recall to replace the cap or reservoir with one that is better sealed.

[225]

Had exactly the same except I moaned to the dealer I was near at the time that after 6k odd miles the car should not need coolant so why should I pay and it should be under warranty. They gave me the bottle in the end but it was also near closing time before Christmas which helped just so I would go away

[Kal101]

Had to do mine yesterday - git the warning coolant low potential over heating and damage etc

Bought some anti freeze from Halfords- actually more expensive than BMW stuff !!!

Just threw in a load and topped up with water - probably 50:50

Was wondering about water free coolant

Found the expansion chamber but didn't know there was a secondary one.

[stefan4]

no such light for me after 10k. I thought fluid top ups were included in the service pack?

[Rukka]

Originally Posted by stefan4

no such light for me after 10k. I thought fluid top ups were included in the service pack?

Not coolant - just oil top ups.

I bought a bottle yesterday so I'll get it done tonight. the light has gone off again so it must have been how I parked it (on a slope) over the weekend.


Really CBA with messing with the dealer for something that will take me 2 mins to do and I know they will find no fault.

If it does it again, then I'll take it in


.