This invention encompasses embodiments for multi-modal integrated simultaneous measurement of various aspects of fluids contained in circulating systems such as automotive reciprocating engines and vehicle transmissions. These circulating systems perform constant internal lubrication, and heat and contaminant removal to protect the internal moving parts from the inherent friction and damage in normal operation. Most commonly this is achieved with fluids based on hydrocarbon and/or related synthetics, which, over time, can lose their protective properties, and vary in their performance or breakdown/decay due to internal and external events. Several components within the lubricant fluid can be measured and can provide insight into the efficacy of the system to perform its designed mission. The mass and level of the fluid may also be monitored on an on-going basis. Described herein is a real-time, simultaneous, integrated, multi-modal sensor system for early warning notification.