Overheating

It could find and fix the leak if the leak is small enough but it could also clog up the small holes in the tubes of the heater core, stick up the thermostat or even some tubes in the radiator. I would not recommend stop leak unless you are stuck in the middle of nowhere, like in a desert, have a leak and only four gallons of water and also happen to have a can/bottle of stop leak, then whenever you make it to civilization again, drain, flush the cooling system trying to get all that stop leak out, top off with plain water, pressure test the system, find and fix the leak, then drain and fill with the proper mix of coolant/water.