2012 Toyota Prius Owners Manual - Page 725

4-3. Do-it-yourself maintenance Coolant The coolant level is satisfactory if it is between the full ("FULL" or "F") and low ("LOW" or "L") lines on the reservoir when the hybrid system is cold. Engine coolant reservoir Reservoir cap "FULL" line "LOW" line If the level is on or below the "LOW" line, add coolant up to the "FULL" line. (→P. 566) ITO43P111 Power control unit coolant reservoir Reservoir cap "F" line "L" line If the level is on or below the "L" line, add coolant up to the "F" line. (→P. 566) 424