The Brent–Dubai Exchange of Futures for Swaps (EFS) is the cleanest market-priced read on whether Atlantic basin crude can profitably move east. A narrowing EFS opens the arb for West African and North Sea grades into Asia; a widening EFS shuts it.
But the EFS alone is not enough. Layer in Suez and Cape routing freight to compute a true delivered netback. When the EFS narrows under $1.50/bbl with stable freight, expect a wave of Atlantic-basin fixtures into China and India within two to three weeks.