Hydrocarbon leakages are a prominent environmental and economic issue in today’s oil and gas transportation infrastructure. In the US alone, over 100 hydrocarbon spills occur yearly, resulting in billions of dollars of civil and environmental damage. To mitigate the impacts of this issue, development and implementation of leak detection systems are prominently applied in industry. However, current state-of-the-art sensor systems utilize indirect methods of sensing that feature poor hydrocarbon selectivity and low detection accuracies of 16-17%. Herein we employ hydrocarbon-soluble polymers in fabrication of sensor designs for direct and selective crude oil sensing. Composite EVA/carbon fiber sensors are fabricated and show 421% sensor responses after 6 hours of oil exposure, while reflectometry sensing via EVA and silicone coaxial cables show sensor responses of 9.71% to 115% after 24 hours of oil exposure. Overall, high efficacy in hydrocarbon leak detection is achieved, validating the sensing effectiveness of hydrocarbon-soluble polymers.