Low coolant? Thermostat not opening? Water pump not circulating coolant?
It could be the radiator, the hoses, a leaking coolant tank or the water pump.
Just pour it into the coolant tank. Don't overfill, use 50% water and get an extra 15lb coolant tank cap.
from a non-mechanic but usually there is some coolant leakage
Low coolant? Heater core airbound, restricted, or plugged? Bad thermostat? Water pump not circulating coolant?
Usually 50 / 50 , up to 60 % antifreeze in colder climates
The radiator on a 98 Buick Century is flushed by turning the petcock to drain the coolant. Water is then flushed through the system until all contaminants are removed.
Anti-freeze is a coolant that should be mixed 50/50 with water
I would say that you are losing coolant somewhere hoses,water pump,radiator.
Regular green antifreeze of any manufacturer will be fine in a 50-50 mix with water
It could be coolant from the coolant tank or radiator, or if it's clear, it's probably just water condensation from the air conditioner.
They are the same in that they don't allow reactor coolant water boiling in the primary water coolant loop. They are different in that in PHWR the moderator is heavy water while in PWR the moderator is normal light water.