Hey guys-time to replace the coolant (i mean the antifreeze of course). I have been using the same liquid for years (dealer approved) - but i have been wondering-
usually when i do it i unplug the small drain plug on the bootom of the radiator-open the cap-and let the coolant drain for a few hours-and then i re-fill the system,drain the air bubbles-and thats it. I have done this a few times in the past-no problems.

but what about the old coolant thats still inside the engine? in the internal heater core? i guess it doesnt drain out.

How do i make sure that ALL of the coolant has been drained from the system before i fill the new coolant? any ideas?