I changed my auto transmission oil 2x and I don't remember seeing any lights showing low-level. Bmw believes that since it is a closed system it doesn't need a dipstick. However, they recommend changing it at 100,000 miles (even though the sticker on the pan states "lifetime"). They also overlooked something, they are assuming your transmission lines/pan/seals will never leak. If and when they do, that will ruin your transmission and you won't know it until it is too late. The art of engineering.