Coolant and water must be phosphate free to prevent corrosion of the aluminum. No coolant will provide corrosion protection when the anticorrosion compounds are exhausted.

Please note that many "green" antifreezes contain (or used to contain) phosphates and silicates as corrosion inhibitors and "water pump lubricants" The phosphate slowly corrodes the aluminum and the silicates precipitate as insoluble scale, both clogging the radiator and grinding away at the water pump.

MB Coolant or one of the "orange" products mixed with distilled water is by far the best, but still change it often, even the "long life" stuff. Coolant is much cheaper than a blown head gasket and warped head!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!