e430guy, Ph is the critical characteristic of Mercedes coolant . As the ph approaches 8.0 coolant should be changed as it erodes alloy engine components and makes plastic parts brittle. The ph of Mercedes coolant in the bottle is approximately 5.6 so that when it is mixed 50/50 with water the ph becomes 7.0 or neutral. The ph of other manufacturers' antifreeze can be as high as 9.0 or 10.0 straight out of the container which is an immediate problem. Swimming pool ph test strips can be used to check the ph of coolant and coolant/water mixtures.

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Fred Hoelzle