Toyota HIGHLANDER HYBRID 2011 Manual page 452

4-3. Do-it-yourself maintenance
Power control unit coolant reservoir
■
If the coolant level drops within a short time after replenishing
Visually check the radiator, hoses, coolant reservoir cap, drain cock and
water pump. 
If you cannot find a leak, have your Toyota dealer pressure test the cap and
check for leaks in the cooling system.
■
Coolant selection
Only use "Toyota Super Long Life Coolant" or similar high quality ethylene
glycol based non-silicate, non-amine, non-nitrite, and non-borate coolant
with long-life hybrid organic acid technology.
U.S.A.: Toyota Super Long Life Coolant is a mixture of 50% coolant and
50% deionized water. (Enabled: -31F [-35C])
Canada: Toyota Super Long Life Coolant is a mixture of 55% coolant and
45% deionized water. (Enabled: -44F [-42C])
For more details about coolant, contact your Toyota dealer.
452
Reservoir cap
"FULL"
"LOW"
If the level is on or below the
"LOW" line, add coolant up to the
"FULL" line.