I suggest you get a hose on the drain point and run about 3 li/min out while you run the heating with boiler stat on low.
Watch colour and when it starts to clear turn off the hot rads one at a time with 5 min gaps until last rad is reached.
Then add X800 and leave it in system for a day running for 10 min per hour then drain out and refill with X100.
Tony
Watch colour and when it starts to clear turn off the hot rads one at a time with 5 min gaps until last rad is reached.
Then add X800 and leave it in system for a day running for 10 min per hour then drain out and refill with X100.
Tony