Recently had spent ton of money fixing my 2011 x5 (35i) had a bad ofhg leak which was causing the coolant reservoir tank to have a muddy mixture. Coolant sensor was bad in that tank supposedly and replaced that tank. 5 coolant flushes a new water pump, thermostat and gaskets, I’m good to go.

Fast forward present say my coolant light is on.. wait for the car to cool down and the coolant is way below the “min” sign inside. Coolant itself is a blue/green color but there this white residue which looks like frost but it’s clearly not since obviously the coolant heats up. What could this be?