An 80 with a 4 cyl holds about 3 gallons, or 12 quarts give or take a pint or two.
I've checked into the evans product. It appears to be propylene glycol and nothing else. I would not want it in my engine for 3 reasons; 1. Lower heat capacity. Pound for pound, it carries less heat than water which can make things hotter if the heat can't move out fast enough. 2. It's much more viscous than water, which is a bigger drag on the engine to turn the water pump. 3. Bacteria. I don't know what they put in it for this problem, but having used it in cooling systems for buildings for 20 years in my old day job, it's a big issue and a major source of corrosion especially on iron and soldered fittings.