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A three-pad dip-and-read test strip has been developed for determining whether the pH, chloride and sulfate levels in engine coolant samples lie within or exceed the recommended ranges. The preferred ranges are 7.5 to 11.0 for pH, below 200 ppm for chloride ion, and below 1500 ppm for sulfate ion. Conditions outside of these limits can lead to corrosion of engine cooling system metal surfaces. A quick and convenient test can determine whether the coolant is suitable for continuing use or should be drained from the system. Extensive performance and stability evaluations of the test pads have been carried out, to ensure that the test strip results agree with reference method results and that test strips are stable under normal storage and use conditions. The test strips were evaluated with different glycol levels, with both ethylene and propylene glycol samples, and under different lighting sources.

A test strip containing three pads for measuring the freezepoint protection, molybdate and nitrite levels in heavy-duty diesel engine cooling systems has been developed for commercial use. The test strip requires no pretreatment or dilution of the sample, other than to allow it to cool to 130 degrees F or lower, and gives results for all three tests within two minutes. The test results are sufficiently accurate, and the strips are stable over extended periods of time, provided the container is kept tightly closed and away from direct sunlight and prolonged elevated temperatures when not in use. The freezepoint test offers an inexpensive alternative to refractometers. Since it can be used with either ethylene or propylene glycol coolants, it is recommended over the use of hydrometers.