2000, with ~225k miles, last week temp spiked & coolant was way low. I refilled, and every driving day since I have to add about 1 qt+. My commute round trip is ~50 miles. I can't see anything obvious. No dripping below the car, no spraying coolant from hoses, radiator seems fine, nothing. The only thing maybe is I might smell something from the interior heater (upstate NY, very cold out) occasionally, but it's almost like I'm dreaming that I'm smelling something as it's so faint and rare. Any ideas why I'm losing around a quart of coolant over a mere 50 miles, with no discernible leaks or system breaches? Thanks