Cowen analyst Sam Margolin said he has a constructive refining outlook despite the current headwinds that include increased China capacity and a Brent/WTI compression. The analyst said the second half of the year should see those headwinds pass and said outside of global demand growth, MARPOL shipping industry regulations are requiring low sulfur marine fuel worldwide, and U.S. Tier-3 gasoline requirements could result in lower octane supply as a consequence of the de-sulferization processes. Margolin favors Valero (VLO), Phillips 66 (PSX), Delek (DK), Marathon (MPC), and Andeavor (ANDV) in the refining space.