Loss of coolant

if you are adding coolant every day then you are experiencing coolant loss
could be from a leaking pump gasket , head gasket or other leaking item
have a compression test done to check for head gasket , cracked head
next have the cooling system pressure tested to find the cooling leak
lastly check the fan, fan relay , fuses and coolant temp sensor unit for correct operation

Possible head gasket gone

Maybe the water pump

Wouldn't just be adding coolant & using it

Find & fix the problem

Adding to the reservoir is fine; it works to regulate the amount of coolant in the total system. When there is excessive coolant (or heat when you have a problem) the excess is purged into the reservoir. Likewise, when the engine/radiator cools down, coolant is sucked back into the radiator. (Hot fluids expand, cool contracts, and thus a vacum is created).
You are addressing the wrong problem, here. Taking the keys away was a good first step. You need to also stop driving the car. Coolant loss is a potentially serious problem, not to mention a pollution issue. Get the car to a mechanic and find the source of the leak now. You can't band-aid this. Maybe it's just a hose, but it could be a radiator. No matter what, leaks don't heal up, they only get worse until some thing fails catastrophically. Lose your cooling = lose your engine. GET IT REPAIRED before it relly costs you.

First, check if coolant is low, as that is often the cause of loss of heat.
Check if the heater core is leaking-if floor on passenger side is damp, it may be leaking. Changing out a heater core can be very easy or very difficult, depending on the design. On some more difficult ones, the entire dash has to be removed. I hope not in your case.
When coolant is full and engine warmed up, feel both heater hoses. Both should be hot, indicating the core is circulating coolant.
Keep looking for a leak, if you keep smelling coolant or have to keep adding.

So the level keeps dropping in the reservoir? If you have to keep adding coolant to the reservoir, the system is leaking or losing coolant somewhere. Have the system pressure tested to find the leak. Is the reservoir itself leaking? When the level gets low enough, first the reservoir will go dry, then the radiator level will start to drop.
Here's how the reservoir works: coolant is under pressure from the radiator cap seal. As coolant heats up from hot engine, it expands, and pressure forces the radiator cap seal up, coolant is forced into the reservoir-remember the hot mark on the reservoir? When car is shut off, coolant contracts, creating a vacuum in top of radiator. This vacuum works to suction coolant back from reservoir into the radiator, keeping the radiator topped up, and coolant should now be at the lower cold mark on the reservoir. It is a closed, sealed system. The only loss of coolant will be a very small amount of evaporation from the reservoir. If coolant level keeps dropping, there is a leak somewhere.

Hi.

Do a compression test and look for symptoms of head gasket problems. If the leak is internal, then the most common cause is a worn head gasket. Water (or coolant) leaks internally through the head gasket reaching the cylinders where it gets vaporized. Symptoms are coolant fluid level going down (with no external leaks), bad performance, loss of compression, overheating, white smoke from exhaust because of vaporized coolant, traces of fuel in coolant reservoir etc.

If there is no head gasket problem and there is no overheating, then the leak is external. Check pump, radiator and coolant lines.

Regards.

Ginko.

Roll the dice, a loss of coolant can burn up a good engine.

Those pesky little bypass hoses in the cooling system tend to go hard and split if they are over 5 years old, allowing coolant loss.

I'm guessing this is a 2.5 v6. Most common problem is a bad distributor, (loss of spark) Make sure as these are fairly pricey. Fuel pumps also go bad but not as common