2010 Toyota Tacoma Double Cab Owners Manual - Page 387
2010 Toyota Tacoma Double Cab Manual
Page 387 highlights
4-3. Do-it-yourself maintenance Engine coolant The coolant level is satisfactory if it is between the FULL and LOW lines on the reservoir when the engine is cold. Reservoir cap FULL LOW If the level is on or below the LOW line, add coolant up to the FULL line.