Do NOT drive your car for even a second if you know you’re out of coolant. It’s as simple as that. If you’re driving and all of a sudden see your temperature gauge skyrocket and a huge amount of steam coming from your engine, stop the car to avoid seriously damaging your engine.
In emergencies, yes. However, you’ll want to make sure that your car is filled with the correct coolant as soon as possible as they are specifically designed to keep the engine cool whilst avoiding corrosion or rust within the cooling system. Water will also boil much quicker than coolant and could cause the engine to overheat.
Note: Tap water can cause mineral deposits to build up inside the cooling system. If you do need to use water to cool the engine in an emergency, try to use distilled water.
As long as both coolants are the same type and specification (read what’s written on the bottle) you will be fine. When mixing different coolants that contain different technology, effectiveness and performance is reduced. Definitely avoid mixing different colour coolants.
A clear plastic bottle sits in your engine bay and displays the amount of coolant your car has. There will be two markers on it, one indicating ‘full’ coolant level, the other the ‘low’ coolant level. When your car has cooled down, check to make sure your coolant level is between these two markers.
When you check the coolant level in the overflow bottle, your engine should always be cold. If you check the coolant when the engine is hot, you may get a false reading as the coolant expands.