If you're working on your cooling system, chances are you're going to need coolant to replace what you lose during your service. We recommend Genuine BMW coolant. BMW's blue G11 coolant is designed to promote heat transfer and prevention of corrosion throughout your cooling system. Genuine BMW coolant is nitrate and phosphate free. Note that BMW coolant must be diluted with distilled water to a 50:50 mixture before adding to vehicle.