Abstract: Systems and techniques that facilitate detecting fuel in oil, lube degradation, and foreign object contamination through optical and/or color characterization are provided. A signature component can generate a digital signature corresponding to a lubricant in a lubrication circuit of an engine. The digital signature can be based on optical or visual properties of a sensor array coupled to the lubrication circuit and exposed to the lubricant, wherein the optical or visual properties of the sensor array can depend on a health of the lubricant. An analysis component can characterize the health of the lubricant by comparing, via a machine learning algorithm, the digital signature with a baseline digital signature corresponding to a desired health-level of the lubricant. In some embodiments, a light emitter component can emit a first light onto the sensor array, and a light receiver component can receive a second light emitted by the sensor array in response to the first light.