So I ran vinegar for a bit, ran it, left it there overnight, drove it a bit. I had about 3L of vinegar in there, rest was distilled water. The drained water vinegar mixture was a bit rusty.
Then I neutralized the remainder vinegar by using some baking soda, I used 4 tea spoons, should had used half that. foamed up quick and at one point was quite pressurized as expected and the little bleeding screw hole became a volcano at operating temps. I then proceeded to clean it up with tap water from the hose, about 20L of that later, what came out was just as clean as what went in. At this stage I was done and added distilled water + green nulon coolant. bleed it. Hopefully this takes care of it.