Putting new coolant reservoir bottle

[Fiat88]

So, I'm waiting for my new bottle to come via Vicks to replace the yellowed slightly melted one. Never replaced a coolant bottle before, so maybe you guys can give me some tips. I have a good idea how to do it,though. Would you guys reuse the old coolant if it looks clean or should I refill the bottle with new stuff. Thanks.

[So Cal Mark]

if it's two years old, replace it. If it's less than that, and doesn't look diluted reuse it