Because of above inter-element interferences, experi descr mentally obtained sulfated ash values may differ from sulfated ash values calculated from elemental analysis. The formation furie of such non-sulfated species is dependent on the temperature of OXIC ashing, time ashed, and the composition of metal compounds present in oils. Hence, sulfated ash requirement generally vol should not be used in product specifications without a clear i v understanding between a buyer and a seller of the unreliability thi of an ash value as an indicator of the total metallic compound content.