Join Date: Jan 2004
Location: Ottawa, Ontario
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I have been using Valvoline Zerex G0-5 coolant, which from what I've read is one of the better coolants. Lots of corrosion protection and long life. I contacted Valvoline directly to ask if this coolant is compatible with my old Mazda and they said it was well suited for the car. Previously, for the first 320,000 kms, I was using plain old green glycol coolant - 50/50 with soft water.
I notice that when any of the orange Zerex drips out anywhere, it dries up into a white powdery residue, unlike green glycol which dries into a sticky thick liquid. Then I read this article on Popular Mechanics website discussing water pump seals:
"Two perfectly flat rings, one stationary and the other rotating with the pump shaft, are pressed together by means of a coil spring. The rings may be made of carbon or may be ceramic, phenolic, porous bronze, cast iron, etc., in any combination. This allows only enough seepage to keep the elements lubricated. It has a weak link, however, in the form of its rubber parts—the bellows that seals the spring and the rubber seat cup between the rotating element and the shaft. If the engine is ever run dry, the temperature of the pump is apt to rise far beyond what the rubber can survive, and a leak occurs. Another possibility is warpage of the sealing elements, also from overheating.
There's conflicting evidence on whether silicates and phosphates from antifreeze, or other hard particles such as casting core sand, can actually damage the seal faces. Engineers have told us the running clearance is way too small to admit solids of any appreciable diameter."
Could the type of coolant I'm using be part of the problem?