Buton Rock Asphalt (BRA) shows potential as a sustainable asphalt mixture, but its high stiffness limits performance. This study evaluates performance improvements in BRA through softening with waste engine oil (WEO) and elastomeric reinforcement with nano crumb rubber (NCR), focusing on rheological response and rutting resistance under aging conditions. Modified BRA mixtures with 15 % WEO and 1.5 %–2.0 % NCR were tested using a Dynamic Shear Rheometer under Pressure Aging Vessel (PAV), Resilient Modulus, and Wheel Tracking Machine conditions. Data analysis employed mechanistic methods, including Modulus Decay, Response Surface Methodology (RSM), and the Multivariate Rational Response Surface Model (MRRSM). Results indicate that increasing temperature decreases the Resilient Modulus across all mixtures. By analyzing Modulus Decay and changes in permanent deformation, the need for NCR additives in aggregate asphalt mixtures can be designed. Under PAV conditions, the Resilient Modulus is primarily influenced by the binder rheological parameter |G|·sin(δ). RSM and MRRSM analysis demonstrate that increasing binder stiffness at extreme temperatures does not necessarily enhance rutting resistance. The integration of WEO and NCR into BRA significantly improves mechanistic performance, a MRRSM serving as a quantitative method for performance-based asphalt pavement design under aging and extreme temperatures © 2026 Elsevier Ltd.