Your photo's are starting to throw me a bit, 'cos i never know which way i'm s'posed to view them from?
I never bother flushing the expansion tank out personally.
I do put Radflush in though and leave it in for 2 or 3 days so the engine heats up and cools down a few times and it gets to move around the radiator properly for a decent clean out.
But it's not recommended to do that in this unsettled cold weather, because there will obviously be no antifreeze/coolant in the system, and you really don't want a block of ice in the morning.
Ha ha,seriously if you click the pic it goes right way up,i should really ask the admins.
I cant believe you've uttered the words 'i never bother'.....you feelin ok today darrsi

,when I was doing it i actually considered foccin it off but this little darrsi devil

popped up by my shoulder saying 'what you playin at noggy, do the job properly or i'll somehow notice!!!' Ha ha
The old stuff was clean,but it was green & new stuff was orange so not sure what colour id end up with,probably grorange!!!!once it was all flushed out i did the old rock the bike back & forth plus every rad hose i took off had some old coolant in or released a bit more pressure & more came out the drain hole.
Lastly i flushed out the system using the garden hose down the filler cap,cheers mr haynes for that one