2003 Nissan XTerra
The lower heater hose was leaking. Note: NOT the radiator hose.
Ordered a replacement but kept driving wile waiting for it to come in. Got to the point that I had to fill the radiator before I left and again before I came home, but was generally able to keep it from overheating.
Didn't refill with anti-freeze, saving for getting the heater hose replaced.
One morning, water poured into radiator leaks out the bottom and never fills. My guess is no anti-freeze let it freeze. Water comes from right between the back of the engine and front of the bell-housing of transmission.
I'm afraid it is fatal. Any guesses what actually happened?