A hydrocarbon contaminant detection system using a polymer film includes a sensor assembly, a syringe and a controller. The sensor assembly includes a cyclic olefin copolymer (COC) film including electrically conductive materials. The sensor assembly can complete an electrical circuit. The COC film can dissolve in a presence of a hydrocarbon contaminant to cause the electrical circuit to break. The syringe can carry a lubrication oil sample to be tested using the sensor assembly. The syringe is operable to contact the lubrication oil sample with the COC film of the sensor assembly. The controller includes one or more processors, and a computer-readable medium storing instructions which when executed by the one or more processors cause the one or more processors to perform operations including operating the syringe to flow the lubrication oil sample onto the COC film of the sensor assembly at a pre-determined flowrate.