Can I use any coolant for my car?
Well, you use the coolant that is specified in your owner's manual. If you just need to top it up, the recommendation is still the same, however it is unlikely to cause any serious problems if you add a litre of a different type of coolant, as long as you follow the manufacturer's maintenance schedule.
What is the purpose of antifreeze coolant?
As well as preventing water from freezing up, antifreeze raises the boiling point of engine coolant to prevent overheating. The stuff also protects your engine from corrosion, aids heat transfer, and prevents scale from building up internally.
How do you use antifreeze coolant?
Loosen the reservoir cap just a little, then step back while the pressure releases. Then, remove the cap completely. If the coolant level is low, add the correct coolant to the reservoir (not the radiator itself). You can use diluted coolant by itself, or a 50/50 mixture of concentrated coolant and distilled water.