Add to Cart Cummins X15 ISX Big Boss Performance Dual Oil Cooler By PDI Performance Diesel MSRP: Now: $4,312.95 Was: Cummins X15 ISX Dual Pass Big Boss Oil Cooler Heavy Duty Oil Cooler Fits Cummins X15 And ISX Engines (1999-2024) Dual High Efficiency Cooler Packs 75% More Oil Cooling Capacity Lowers Peak Oil Temperature 20-30 Degrees Thermostat And Bypass Valve... MSRP: Now: $4,312.95 Was: Add to Cart