Despite years weekly inspections under the hood, I noticed something about the coolant tank tonight that I'd never noticed before. I always look at the end of the coolant tank to check the level - where it says "Cold Fill Max/Min ". I just realized that inside the tank, immediately to the left of the pressure cap, there is an internal vertical divider. And all of the tank that is on the right side of this divider - which comprises about 75% of volume of the tank - is empty !!! What the heck is up with that ? What have I overlooked all these years ? Phil