The only approved fluid is the MB stuff, worth the cost in my opinion. Use about a 50/50 mix of coolant with distilled water. I found that my car came from the factory with a 55/45 coolant/water mix, so I used that ratio.
Take the coolant cap off, then loosen the drain plug on the radiator and the block drain plug under the exhaust manifold.
Tighten everything after it is all drained, then slowly add coolant to the reservoir.
Make sure the system is completely bled of air. To do this, fill the expansion tank all the way to the top until it is about to pour out, the gently squeeze the coolant hoses to burp some of the air out. The keep the tank full, start the engine and let it run up to temp while making sure the tank is overflowing full.
After this is done, let the car cool off and check the coolant level and drain some if necessary.
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record