This invention relates to methods for determining whether or not to discard a sample of oil based on the presence of polar compounds in the oil and devices to be used therewith. In a preferred embodiment a test strip including an adsorbent affixed to a backing is spotted with a polar indicator. A sample of oil is positioned on a heat conducting device supporting the test strip and the oil is allowed to migrate over the adsorbent material thereby displacing the polar indicator in an amount related to the amount of polar compounds in the oil. This displacement is correlated to the amount of polar compounds in the sample.