This study investigates the functional modification of ternary ethylene-propylene rubber (EPDM) with benzamine phenol formaldehyde (BPFO) to enhance its properties and compatibility with butadiene-nitrile rubber (NBR). Samples with varying compositions were prepared, and their rheological properties were analyzed to identify optimal blends. This study's novelty stems from its simultaneous improvement of EPDM's compatibility with NBR, mechanical strength, thermal resistance, tear strength, and metal adhesion, along with the determination of optimal blend ratios for industrial applications. The addition of 4-6 parts by weight (p.w.) of BPFO to SKEPT-60 led to a 12% increase in fracture strength and up to a 30% improvement in metal adhesion. This range was found to be optimal. The introduction of functional groups (–OH, –NH₂, –CH₂–) enables cross-linking, increases stiffness and mechanical strength, and enhances thermal stability. Furthermore, BPFO improves the compatibility between NBR and EPDM, reducing swelling in aggressive environments due to its aromatic structure. The resulting modified rubber compositions have numerous industrial applications, including automotive components, fuel and oil pipelines, compressor seals, and machinery parts in petrochemical, aviation, construction, and household industries. They are especially suitable for high-performance sealing and insulating applications in harsh conditions, offering improved chemical resistance, durability, and long-term reliability.