I always start from a completely drained system. I also keep an empty antifreeze jug stashed for mixing purposes. I pour in about 40-45% AF and top off with water, then pour that mix into the system after checking the ratio with the tester. Continue the extra jug mix method until the system is full, then add a bottle of Redline's Water Wetter.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.