I don't have any experience with the factory ford coolant but as far as dexcool and the regular green "they can be mixed without any issues." I have done this with every car I have owned and never had any issues ever. Before doing this with a brand new Impala that my wife purchased in 2000 I had problems with the dexcool gelling up. So as far as it gelling up from being mixed this is false. Both are glycol based coolants with dexcool having the additives that green doesn't far from being any different other than the additives.