2010 Lexus GS450h radiator cap

460
4-3. Do-it-yourself maintenance
GS_HV_U (OM30C81U)
October 13, 2015 12:41 pm
Engine compartment
■12 volt battery
P. 4 7 0
Engine oil level dipstick
(P. 4 6 2 )
Engine oil filler cap
(P. 463)
Brake fluid reservoir
(P. 468)
Fuse box (P. 4 9 6 )Washer fluid tank
(P. 4 74 )
Gasoline engine/power 
control unit coolant 
reservoir (P. 466)
Electric cooling fans
Condenser (P. 468)
Radiator (P. 468)

466
4-3. Do-it-yourself maintenance
GS_HV_U (OM30C81U)
October 13, 2015 12:41 pm
Coolant
The coolant level is satisfactory if it is between the “FULL” and “LOW”
lines on the reservoir when the hybrid system is cold.
Reservoir cap
“FULL”
“LOW”
If the level is on or below the
“LOW” line, add coolant up to the
“FULL” line.
■If the coolant level drops within a short time after replenishing
Visually check the radiator, hoses, reservoir cap, radiator cap, drain cock and water
pump. 
If you cannot find a leak, have your Lexus 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 Lexus dealer.

467
4-3. Do-it-yourself maintenance
4
Maintenance and care
GS_HV_U (OM30C81U)
October 13, 2015 12:41 pm
CAUTION
■When the hybrid system is hot
Do not remove the radiator and reservoir cap.
The cooling system may be under pressure and may spray hot coolant if the cap is
removed, causing burns or other injuries.
NOTICE
■When adding the coolant
Coolant is neither plain water nor straight antifreeze. The correct mixture of water
and antifreeze must be used to provide proper lubrication, corrosion protection
and cooling. Be sure to read the antifreeze or coolant label.
■If you spill coolant
Be sure to wash it off with water to prevent it from damaging parts or paint.

582
5-2. Steps to take in an emergency
GS_HV_U (OM30C81U)
October 13, 2015 12:41 pm
■Overheating
In the following situations, your vehicle may be overheating.
●The engine coolant temperature gauge enters the red zone or a loss of power is
experienced.
●Steam is coming from under the hood.
●The message “HYBRID SYSTEM OVERHEAT” is displayed on the multi-infor-
mation display.
CAUTION
■To prevent an accident or injury when inspecting under the hood of your vehicle
●If steam is seen coming from under the hood, do not open the hood until the
steam has subsided. The engine compartment may be very hot, causing serious
injury such as burns.
●Keep hands and clothing away from the fan and engine drive belt while the hybrid
system is operating.
●Do not loosen the radiator cap while the hybrid system and radiator are hot.
Serious injury, such as burns, may result from hot coolant and steam released
under pressure.
Add coolant if necessary.
Water can be used in an emer-
gency measure if coolant is
unavailable. (P. 5 9 3 )
Have the vehicle checked at your nearest Lexus dealer as soon as pos-
sible.
STEP6