Antifreeze leaks in places that water won't leak. Antifreeze has a higher boiling point than water but that really doesn't help. A model A doesn't have to be running at 212 degrees to be running hot. The model A actually runs cooler with water. Some sing the praises of antifreeze fighting rust. Soluable oil or water pump lubricant will keep the system free of rust and help lubricate the pump at the same time . I use it for that reason. It will run cooler with straight water but you won't have rust protection. It takes more than a table spoon. I buy it in small bottles maybe 1/4 pint or thereabout. Different parts houses sell different brands. Gunk brand is lower cost here. Prices range from less than two dollars a bottle to just over five, depending on brand and who is running the parts store. If you have freezing temps you either need to use antifreeze or drain the system.