Ron, there is no difference between Prestone, Zerex or MB anti-freezes. That is what my dealer told me. I know this stuff is supposed to last 5 years or longer. Considering the low cost of anti freeze, I change every year. I added a Prestone reverse flushing kit to my cooling system. It goes in the heater hose. If allows me to attach a garden hose to the fixture and reverse flush the cooling system. I open the drain on the block and radiater, remove the radiater cap, turn the water on slowly, go drink a cup of coffee and let nature do it's job. I have a 1987 300E with 169,000 miles, the waterpump was replaced at 109,000 miles, the core plugs are still solid and the radiater still looks good. You may consider Red Line Water Wetter. It is a surfactent and it is supposed to do something to the water. Oh well that's how I do it. Happy Trails Beep Beep from Houston.

Donald
all wet