BMW Questions? Ask a BMW Repair Expert for Answers.
The fluid you have described sounds like coolant. BMW coolant is blueish and slippery like oil. And with the light on intermittently this makes sense that you have a leak. The reason it shows full is when the system gets hot the system is pressurized and looks full when you open the cap. As for the cause of the leak there is a large belly pan under your engine with a small hole where you describing seeing liquid. It could be waterpump or thermostat or radiator or expansion tank. To be honest I would replace all of the items I commonly upsale all of them at once because they are a common failure on your vehicle with more then 100k in miles.