2010 Toyota 4Runner Owners Manual - Page 525

4-3. Do-it-yourself maintenance Engine coolant The coolant level is satisfactory if it is between the "F" and "L" lines on the reservoir when the engine is cold. Reservoir cap "F" line "L" line If the level is on or below the "L" line, add coolant up to the "F" line. (→P. 603) CTH43AS108