Catastrophic crude oil spills excite media interest but operators usually manage greater losses from daily shipping operations single-handed. This paper invites energy policy makers to re-embrace daily oil losses. It categorises them, discusses physical and accounting measures and reports empirically crude oil loss patterns and factors influencing them on some recent North Sea voyages. Losses varied with crude-type, measured by its vapour pressure, AN gravity and viscosity, but evaporative loss in transit was low on these short voyages. Where sediment and water content influenced losses or error rates are exceptional, measurement techniques should be revised. Varying losses across load and discharge ports infer revisions to tank and terminal designs. Empirical evidence revealed reduced losses in double hull vessels, supporting clingage theories, although insufficient pre-1985 or segregated ballast tank vessels were in employment to permit meaningful comparisons with newer ships. Calculating and applying vessel experience factors assists comparison and loss prediction. To minimise losses requires closer involvement of policy makers with operators. (C) 2003 Elsevier Science Ltd. All rights reserved.