Coolant swap to G12 Evo - How to drain drain?

[Bluest]

I ditched the silica bag today and attempted to swap over to G12 Evo. However, I could only drain about 2.5l from the system and I believe that the capacity is about 8l. So how do I drain it fully to do a proper swap?

[Rudedog]

Very apt timing as I'm planning to this very soon - I had my heater matrix replaced and although the coolant is clear it's not a bright pink but slightly orange which I've read can happen but I'd rather replace knowing I have the correct mix of G12 Eco.

I've trawled the internet and found this video, which I'm going to probably follow - although I will flush through with de-ionized water before introducing the mix.

https://www.youtube.com/watch?v=wfECBbTP7Tw&list=LL&index=142

Sounds like the trick is to do this on a pre-warmed engine so the thermostat is open plus have the cabin heating on high so all of the old coolant can be removed.