I propose you drive by your BMW support Centre and request them to top it up with coolant. It is totally free. Or else You'll have to order a "BMW accredited" coolant mix which I have little interest in hoping to determine. Replenishing the procedure with the appropriate coolant and https://autocollisionrepairandref18381.ampedpages.com/types-of-coolant-for-bmw-335i-fundamentals-explained-54770617