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For several years now, organic acid based coolants and heat exchange fluids have been introduced on the automotive and industrial market place. The organic acid based coolants provide improved high temperature aluminum corrosion protection and longer drain intervals when compared to traditional coolants. In order to evaluate the organic acid based coolant quality in the field; the end user needs to be able to check several physico-chemical parameters of the coolant. First of all the amount of carboxylate based inhibitors should be determined because the customers can top the system with water. As a result the carboxylates can drop under the minimum required inhibitor level.

Previous studies examined the effect of low levels of silicate (∼<75ppm Si) on hot aluminum corrosion protection. The corrosion protection provided by different coolant technologies was evaluated at different silicate levels. The results indicated that small amounts of silicate have a negative effect on the corrosion protection of aluminum. This work will examine these results and evaluate the effectiveness of different laboratory tests for determining coolant “compatibility.” Results will be examined from several bench and fleet tests showing the effect of coolant mixing on the corrosion rates in various environments. The bench test results will include laboratory glassware and dynamic tests that have been used historically to evaluate coolant compatibility. Differences between the test methods will also be evaluated to determine the relevance of each test procedure in light of the fleet observations.