You should only need one gallon of coolant. That mixed with clean (distilled??) water should yeild about a 40-45% coolant/H2O ratio.
If the system had other than MB coolant, and you plan on using the MB coolant now, be sure to flush the system multiple times. I've heard that mixing the two can result in solid participate that could clog up the system.
It is best to pre-mix the coolant and H2O. I usually have an empty coolant jug and I will pour 1/2 gallon of new coolant into the old jug, then top it off with water. Sahke to mix then start filling the system. Do the mix until all coolant is used then top up with straight water. A bottle of Water Wetter can't hurt either.
'73 280SEL 4.5 (9/72)- RIP
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'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
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