My MB has the green stuff in it and I am going to change it here at home. I am going to get the Zerex coolant.

Do I just need to simply drain the radiator, then refill with the Zerex? Not sure how to flush it myself, unless I just leave the drain out and pour some water through it to get out as much as I can?

Also, I live in an area where it dont get below 5°, even in the harshest cold weather outbreaks... would one gallon be enough, then then refill the rest of the way with distilled water? (BTW, its a W126 with the M103 engine).

Thanks.