You must mean additive.
The same, only different.
Advice from a career mechanic:
If your radiator leaks, replace it.
If your heater core leaks, replace it.
If a hose leaks, replace it.
If you have an internal leak in your engine, like a head gasket leaking, then you need to remove the warped cylinder head and get it repaired or get a replacement, and reinstall it with a new cylinder head gasket.
Where is the leak?
Do you know?
Do you see leakage, wetness, steam or dripping?
Or is it milky looking engine oil?
Or is it an empty coolant reservoir all the time?
Sometimes the cure is simple and inexpensive. Sometimes the cure is straightforward, but not inexpensive.
Which car do you have?
Tell us more.