Realy too little information. 'Sloshing', is this for a mobile (vehicle not cellphone) project. The contents and use or action? Are you trying to determine when your beer can is almost empty, and time pop open a fresh one? Would that be pretty obvious (unless you've had a few to many already), then again shouldn't be driving anyway... Will the fluid be left to evaporate, and you need to refill the container?
Temperature sensing, what material is your tank? An aluminum beer can may not provide a big temperature difference at fluid level, unless the fluid is much warmer or colder than the ambient temperature. Basically, if the can is at room temperature, and the fluid is at room temperature (hate warm beer)... Over time the temperature will equalize.