Densities, speeds of sound, and isobaric specific heat capacities were measured for three polyol ester base oils and one fully qualified lubricant. Density and speed of sound were measured at ambient pressure over the combined temperature range 278.15 to 343.15 K. Heat capacity was measured over the combined temperature range 263.14 to 492.15 K; the specific temperature range varied for each fluid and was selected to avoid potential phase transitions. Measurement results for these three properties, as well as calculated adiabatic compressibilities, have been reported. Experimental results for the four fluids were compared with one another and with available literature data.