coolant ratio to distilled water?

[Bob G ✝︎]

Got a question. What is the ratio of  mixture for filling the radiator after draining the old fluid out. I have one gallon of Mercedes-Benz factory coolant new is this enough? how many gallons or quarts of distilled water should I mix when refilling the cooling system.
Also what is your take on the Mercedes -Benz powder to decalifing the crud and hard water deposits in the system. Is it worth using how much do I mix to regular water and  should I drive the car for a short drive and then let it cool down and drian out? Also what is your take on redline water wetter?

P.S. car is not running hot . I have the old green stuff in the radiator and would like to finally change it.

Thank You
Bob Geco
1968 280SL

[waqas]

Hi Bob,
Coolant to water ratio should nominally be 50/50, but if you're worried about overheating then slightly more water is better (e.g. 40/60).

You might as well backflush the cooling system whilst you're at it; would be good for removing some of those deposits. (instructions somewhere on the site).