Both heavy-oil lines gave back gains in the night session. Fuel oil settled at 5,200 yuan/tonne, down 1.79% on the day; bitumen at 4,850 yuan/tonne, down 0.88%. The "fuel oil holds its premium to bitumen" read from the 14:00 window broke after hours — the FO-BIT spread pulled back from ¥393/t to ¥350/t, a 43-yuan contraction.

A narrower spread reshuffles where refiners send residue. Fuel oil fell faster, signalling that buying interest at the bonded bunker-blending end cooled overnight; bitumen followed but by less, still supported by social-inventory drawdown as the road-construction window closes. Refiners have fresh reason to route vacuum residue into coking for yield.

Brent at 109.587 and WTI at 100.2 put the spread at 9.39 dollars, both crudes lower (Brent -1.04, WTI -1.53). The yuan firmed to 6.667, off 0.033; run through the landed-cost formula and East China delivered crude lands near ¥731/bbl, a touch softer than midday. Feedstock economics did not worsen, so the residue reallocation is marginal rotation, not cost-driven.

For SNSUC's thirteen categories, the heavy-oil pricing curve flipped from "premium divergence" to "synchronized pullback" within the day. The denominator on the listing formula (Brent times FX times 7.33 times grade) still carries the FX dividend, so quotes do not need to chase the drop.