One thing that we should consider when posting either stories or advice is
the consideration for how things can be interpreted especially by those that
are less knowledgeable or experienced. It is bad advice to let someone think
that it is OK to keep operating the engine when the low coolant warning
light is on as long as the gauge says the temperature is still under
control.

Proper operation of the cooling system requires that the engine assembly is
always completely filled and pressurized. The coolant being pressurized
prevent localized boiling, (micro vaporization) and keeping everything
submerged is obvious. The low coolant light not only indicates a significant
loss of coolant but most likely a loss of pressure also.  The level sensor
is set so that the feed to the water pump should still be sufficient to
prevent it from cavitation but how long this is true depends on the size of
the leak. At this point the cooling system is compromised.

The gauge continuing to show "normal" just indicates the coolant is still
flowing enough for the radiator to do its job. If the coolant flow stops the
gauge may even drop until whatever coolant left in the engine begins to
produce enough steam that the steam travels and gets to the gauge sensor. At
this point the pressure cap may not relieve enough volume and failed hoses
and manifolds become the blame if not an additional failure point.

While the engine is operating with the coolant level dropping the tops of
the cylinders and heads go dry and heat up unevenly. Studs get pulled, the
gaskets get cooked, and if driven too long and hard bad things happen. The
engine at this is suffering a trauma and even if it appears OK after repairs
it may never be the same.

Dennis