Transverse engine, so left is front to me. Intake manifold or headgasket are the first thoughts. With age of it, a softplug (freezeplug) may be rotted.
Sounds like head gasket is leaking
possibly the water pump
coolant sensor replacement need it
12.5 quarts
When that happened on my 97 Lumina the coolant was leaking into the engine, and the light came on even when I added coolant because the whole system was just messed up. I had to take it in to the dealership and it cost 1,300 to fix it, so get it in ASAP before more damage happens.
It could be the coolant overflow tank that is leaking.
If the pump is leaking or noisy then assume it is failing.
Heater core, windshield, or a clogged cowl drain line. If the liquid tastes sweet it is coolant and the heater core is leaking. Heater core must be replaced. If not, it is one of the other 2 problems.
The heater core has failed and is leaking engine coolant.
i had this problem the intake manifol gasket is blowed
A 50/50 mix of water and antifreeze
Could be low on coolant.