A process is described for increasing the storage stability of biodiesel by metering a liquid stock solution which comprises 15 to 60% by weight of 2,4-di-tert-butylhydroxytoluene dissolved in biodiesel into the biodiesel to be stabilized up to a concentration of 0. An auxiliary device can be used to read data stored in the semiconductor memory device without going through the access device. The luminance observation value calculating unit calculates a luminance observation value based on an integration result in the luminance integrating unit. This indicator displays the temperature of the contents of the supply container so that a user can ensure proper dispensing of the reactive components.