Do yourself a favor right now. Go out and look at the color of the antifreeze in your Benz (Make sure the engine has cooled before opening the coolant cap). Is it by chance GREEN? If you have anything other than the pale orange Mercedes antifreeze in your cooling system, please read on because you may be harming your engine! As a bit of background, antifreeze is in many ways a miracle formulation, because it not only lowers the freezing point of water, it also raises the boiling point, assuming the correct 50/50 mix of antifreeze and water.
George Murphy, a member of the MBCA National Technical Committee, strongly urges that only genuine Mercedes antifreeze (properly mixed with water) should be used in your car because it contains special additives to keep the coolant from corroding your engine block, radiator, and engine heads. Apparently Mercedes antifreeze contains buffers to keep the pH of the coolant as close to neutral as possible, which then prevents corrosion and leaching of the engine. pH is a measure of the relative concentrations of acids versus bases in a liquid. Other name brand formulations, while claiming to be specifically formulated for aluminum engines, do not contain the correct pH buffers.
While genuine Mercedes coolant is a little more expensive at $10 a gallon vs $6 for the "Green Stuff", think of it as extremely cheap insurance to extend the life of your M-B investment. Also note that Mercedes recommends changing the coolant at least once every two years. Promise yourself you will check your coolant and have it drained and refilled with the Orange stuff. Those of you with the correct fluid, pat yourselves on the back and worry about collecting your 155,000 mile pin.
Steven Rae, Technical Advisor