original poster: if you can't find bmw coolant at a price you are willing to pay, and you only need a partial refill, just get some prestone all-makes antifreeze (IIRC, bill was the first one to suggest doing this) and use it until your next flush, then use das blau if you want. don't bother mixing the g-05, too much work for too little, since you'd have to go out of your way anyways.