The base oil market shows structural tightening: the mainstream spot price of HVI 150 in East China is ¥8,240/t, up ¥170/t (+2.1%) from the previous day, while the theoretical landed import parity stands at ¥7,875/t — narrowing the spread to ¥365/t. The key drivers are dual supply-side contractions: first, increased refinery turnaround activity domestically, with Sinopec Maoming and Zhenhai Lubricants Hydroprocessing units recently entering their annual maintenance cycles; second, a passive narrowing of the import window — although Brent and WTI fell by 1.21% and 1.54% respectively, the front-month fuel oil futures surged 6.38% intraday, directly raising raw material procurement costs and freight allocation benchmarks for overseas blended base oils (especially Group II+), eroding their landed price competitiveness. Demand-side growth remains muted: extended oil change intervals in the automotive aftermarket and subdued terminal restocking keep dealer inventory levels in East China within a neutral range. However, structural mismatch is emerging: low-viscosity HVI 500N prices remain firm amid the transformer oil seasonal uptick (+¥210/t weekly), while high-viscosity HVI 150 gains support primarily through refinery turnaround spillover. For SNSUC clients, the import substitution window is narrowing; if the RMB exchange rate holds near 6.67, immediate price-locking is advised for SK Group II base oil orders scheduled for November arrival, to avoid further margin compression from rising fuel oil costs. A bullish signal is triggered when the HVI 150 spot price breaks above ¥8,400/t.