Over the past year, refining profit margins have been quite volatile. As an example, Brent crude oil/gasoil calendar swap crack spreads have traded as high as $20.56/BBL and as low as $12.12/BBL, averaging $16.17/BBL. Crack spreads on other crude oils (Dubai, WTI, Light Louisiana Sweet, etc.) and various refined products (diesel, gasoline, jet fuel, etc.) have been similarly volatile.