I'd personally incorporate as much as a few pint or so of distilled h2o.. any more and I'd pick up some coolant to mix. if it goes off once again, carry it on the seller. its probably just evap loss of the drinking water portion of the coolant mix. glycol https://simonuplar.blog5.net/68987792/rumored-buzz-on-types-of-coolant-for-bmw-335i