There has been much debate on this forum as to what coolant to use, so I won't start that up. Whatever coolant you wish to use, CHANGE IT!

Simply, drain the block at the right side behind the exhaust manifold and the radiator drain on the right side rear bottom of radiator tank. After draining, fill with water and keep flushing 'til the water comes out clear, then fill with antifreeze. Some cars have a vent on the top of the thermostat housing to allow the coolant to fill without air pockets before starting the engine.

You should flush it annually.

Have a great day,