<p>This study investigates the nonlinear, asymmetric, and regime-contingent determinants of fuel oil prices across three major European hubs: Antwerp, Barcelona/Valencia, and Rotterdam. It contributes to the literature by being the first to jointly model fuel oil price determinants across these key ports using a multivariate quantile-on-quantile framework that captures tail-specific and regime-dependent spillovers absent in existing models. Employing a dual-quantile Granger causality approach, the research examines the transmission of macrofinancial indicators, clean-energy sentiment, and policy uncertainty across the fuel–oil return distribution. Within this framework, causality is interpreted in the Granger sense, reflecting predictive patterns rather than structural identification. The findings reveal significant cross-country heterogeneity, confirming that fuel oil pricing is profoundly shaped by state-dependent effects. Specifically, the study documents incomplete and regime-specific pass-through from crude oil and exchange rates. In extreme market regimes, such as the upper tail of the price distribution in the Netherlands, the magnitude of the crude oil impact is up to three times larger than at the median, indicating pronounced tail amplification. These insights provide a foundation for developing state-contingent risk management tools, such as environmentally linked derivatives, to navigate fuel price formation under global decarbonization pressures.</p>