PNEUROP Test: A procedure where a sample of oil containing iron oxide as a catalyst is aged by being held at 200 C for 24 hours while air is bubbled through it. At the end of the test, evaporation loss and the Conrad Carbon Residue (CCR) of the remaining sample are determined. The loss must not exceed 20% of the original sample. The test is believed to correlate the tendency of compressor oils to form deposits on valves.