yea n no. when changing the bottle it would be better to drain n change the coolant too. change the bottle and connect it up to pipes etc, once u done this take the hose off at the bottom of the radiator to drain the rest off the coolant re-secure the pipe with new hose clip (if applicable),put 1.5 litre of coolant in the bottle and top up to max with hot water.at the gearbox side of the engine u will see coolant pipes one should have a bleed screw on the pipe take the screw out ( if u cant see one dont matter) turn the heaters to HOTTEST pos on FULL speed and point the blowers to the window and start up the car top up the bottle and watch for coolant to come out of the bleeder on the pipe (may take a min or so)once coolant coming out put the screw bk on and keep topping up water to max sit in car, on slighty revvng the engine feel for hot air at the window once hot/warm air is there keep water topped up to max level put coolant cap on, heaters off switch engine off leave for 10 min and check level, it may drop a little top up as req