The Amsoil turned up today so getting sorted to do the fluid change. I've looked at a few pump options and I'll be buggered if I'm paying the asking price for the majority of fluid filler bottles out there. So, I've used these sprayers from Bunnings on many occasions and thinking that this should do the job well.
https://www.bunnings.com.au/aqua-sys...r-kit_p2960992
I'll just pop the hose off before the steel wand and then get it happening. Let me know if you see any issues or have a better alternative but at under $10 this thing is looking good.
EDIT; Another option is any cheap squeeze bottle. Found this one on eBay. 1L capacity. Probably lots more out there with a bit of lateral thinking.
https://www.ebay.com.au/itm/Dispense...r=521795772512