[MuhammadR]

Hey guys. Doing a coolant drain on my car. I first drained the small radiator by the right tire, and it was green. But then I drained another hose near the bottom of the engine, and it was light yellow! Any idea what this could be?

I’ve attached the hose that I pulled to get this yellow color. It smells very similar to the green coolant and has the same liquid consistency.

Any ideas? The car has 52,000 miles on it.

[visionaut]

AFAIK, BMW coolant is blue. Common commercial coolants are yellow. Yellow + blue = green?

[AspektUSA]

Coolant breaking down, time to replace.

Prior to 2019 BMW used blue G48 coolant, then transitioned to the green HT-12 stuff.

[MuhammadR]

Originally Posted by visionaut

AFAIK, BMW coolant is blue. Common commercial coolants are yellow. Yellow + blue = green?

Originally Posted by AspektUSA

Coolant breaking down, time to replace.

Prior to 2019 BMW used blue G48 coolant, then transitioned to the green HT-12 stuff.

Yep, you’re spot on. The hose I pulled off was part of the low temp circuit. I did multiple rounds of flushing and bleeding to complete the coolant service.

[MuhammadR]

Originally Posted by visionaut

AFAIK, BMW coolant is blue. Common commercial coolants are yellow. Yellow + blue = green?

After doing some research, this was degraded green coolant. All BMWs after 2018 use HT12 green coolant. Before 2018 is the blue you are referring to. The yellow coolant came from the low temp circuit (the small expansion tank), and the dark green came from the high temp (big expansion tank). Regardless, it is supposed to be bright green so both fluids were deteriorated.