First test the specific gravity of your anti freeze to determine what frost protection you have, it may not be necessary to change the coolant at all. If you look around the engine
you should see at least 2 small drain cocks on the block, to drain the anti freeze mixture these need to be opened until no more fluid runs out. I would recommend treating the cooling
system with a radiator cleaner, then flush with fresh water
before refilling with anti freeze mixture.
NEVER use plain water for the cooling system, anti freeze mixtures lubricate the water pump, prevent rust and keep liner seals
in good condition.