Blue coolant is now slowly turning reddish.

I have not had any problems with G48/G11, ( G48 and G11 are basically the same ) been using it for a while already and it has stayed a nice inky blue color in both my cars.


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So as a follow up on this thread i would like to point out that after approx 13k miles the back then new basf g48 is turning reddish again when i look into the coolant reservoir.

I will suck some coolant out tomorrow with a glycol meter to get a better view.

I have been trying to search if other people are having this issue and although i can find some cases no one seems to get an awnser.

These bmw engines run pretty hot with their advanced cooling system so they can run up to 110' degrees Celsius. Most cars run at around 88 degrees celcius.

Maybe this somehow makes it change its colour due to degrading etc..

Or maybe its caused by combustion gases entering the cooling system, however my car doesnt have a leaky headgasket so i doubt that.

The block is magnesium/alluminium, the heater lines are rubber/plastic and so is the radiator. There is no steel in the system so it can't be rust from steel.

It has an atf fluid heat exchanger but if there was oil in the coolant it would look milky which it clearly doesn't.

If somebody has any clue please let me know.
I know are in the system from something like a bad cap or excessive heat can cause coolant to have reddish tint. If it is all okay try a different brand which meets the spec.
I have never noticed a color shift of G48 in either my old 328 or in my Mini. Blue/green if mixed with red would look more dirty red/brown than pink. To me, the Glycomat looks like it has G12 or G13 in it.