The close flipped the internal pricing of the heavy-oil chain. Fuel oil settled at ¥4,976/t against bitumen at ¥4,499/t, a ¥477 premium that erased the roughly ¥400 bitumen premium seen through the morning.

The driver is not total demand but how residue yields are split. The VLSFO-HSFO spread still carries the IMO2020 compliance premium, and independents are shifting vacuum residue away from cokers toward low-sulphur bunker blending, pulling coker feed supply and moving the fuel oil leg first.

The bonded-bunker versus ordinary-trade bunker spread is also widening: bonded product avoids the import quota and import-stage tax, serving both transshipment and bunkering. For SNSUC's seven-grade crude transshipment, this marginal shift matters more than the absolute oil price because it decides the downstream outlet for the crude sitting in the bonded tank.

Bitumen did not follow. The road-construction off-season and high plant inventories keep its crack spread pinned low. A loose-tight split inside the heavy-oil chain is exactly what reversed the ratio into the close.