2018 LEXUS RC300 coolant temperature

4056-3. Do-it-yourself maintenance
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 6
Maintenance and care ■
Intercooler coolant reservoir (RC300)
The coolant level is satisfactory if it is between the “F” and “L” lines on the res-
ervoir 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. 526)■
Coolant selection
Only use “Toyota Super Long Life Coolant” or a similar high qu ality 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 mixt ure of 50% coolant and 50% deionized water.
(Minimum temperature: -31  F [-35  C])
Canada:
“Toyota Super Long Life Cool ant” is a mixture of 55% coolant and 45% deionized water.
(Minimum temperature: -44  F [-42  C])
For more details about engine coolant, contact your Lexus dealer. ■
If the coolant level drops within a short time of replenishing
Visually check the radiator, ho ses, engine and intercooler coolant reservoir caps, drain
cock and water pump.
If you cannot find a leak, have your Lexus de aler test the cap and check for leaks in the
cooling system. 1
2
3

4517-2. Steps to take in an emergency
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 7
When trouble arises ●
Fluid leaks under the vehicle.
(Water dripping from the air co nditioning after use is normal.)●
Flat-looking tires or uneven tire wear ●
Engine coolant temperature gauge cont inually points higher than normal.●
Changes in exhaust sound ●
Excessive tire squeal when cornering ●
Strange noises related to the suspension system ●
Pinging or other noises related to the engine ●
Engine missing, stumbling or running roughly ●
Appreciable loss of power ●
Vehicle pulls heavily to one side when braking ●
Vehicle pulls heavily to one side when driving on a level road ●
Loss of brake effectiveness, spongy f eeling, pedal almost touches the floorIf you think something is wrong If you notice any of the following symptoms, your vehicle probably needs
adjustment or repair. Contact your Lexus dealer as soon as possible.
Visible symptoms
Audible symptoms
Operational symptoms

4677-2. Steps to take in an emergency
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 7
When trouble arises Indicates a malfunction in:
• The SRS airbag system;
• The front passenger occupant classification system; or
• The seat belt pretensioner system
A buzzer also sounds.
 Have the vehicle inspected by your Lexus dealer.
Indicates a malfunction in:
• The ABS; or
• The brake assist system
A buzzer also sounds.
 Have the vehicle inspected by your Lexus dealer.
Indicates that the engine coolant temperature is too high
A buzzer also sounds.
 P. 526Warning message Details/Actions(U.S.A.) (Canada)

526 7-2. Steps to take in an emergency
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U)●
The engine coolant temperature gauge (  P. 91, 96) is in the red zone or a
loss of engine power is experienced. (For example, the vehicle speed does not
increase.) ●
“Engine Coolant Temp High Stop in a Safe Place See Owner's Manual” is
shown on the multi-information display. ●
Steam comes out from under the hood.
Stop the vehicle in a safe place and tu rn off the air conditioning system, and
then stop the engine.
If you see steam:
Carefully lift the hood after the steam subsides.
If you do not see steam:
Carefully lift the hood.If your vehicle overheats The following may indicate that your vehicle is overheating.
Correction procedures 1
2

5297-2. Steps to take in an emergency
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 7
When trouble arises Add coolant if necessary. Water can be used in an emerge ncy if coolant is unavailable.
Start the engine and turn the air conditio ning system on to check that the radi-
ator cooling fans operate and to check for coolant leaks from the radiator or
hoses. The fans operate when the air conditioning system is turned on immediately after a
cold start. Confirm that the fans are operating by checking the fan sound and air flow.
If it is difficult to check these, turn the air conditioning system on and off repeatedly.
(The fan may not operate in freezing temperatures.)
If the fans are not operating:
Stop the engine immediately an d contact your Lexus dealer.
If the fans are operating:
Have the vehicle inspected at the nearest Lexus dealer. 5 
Engine (RC350/RC300 AWD) 
Engine (RC300)
Engine (RC F) 
Intercooler (RC300)
6
7

530 7-2. Steps to take in an emergency
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U)WARNING ■
When inspecting under the hood of your vehicle
Observe the following precautions.
Failure to do so may result in serious injury such as burns.●
If steam is seen coming from under the h ood, do not open the hood until the steam
has subsided. The engine compartment may be very hot. ●
Keep hands and clothing (especially a tie, a scarf or a muffler) away from the fans and
belts. Failure to do so may cause the hands or clothing to be caught, resulting in seri-
ous injury. ●
RC350/RC300 AWD: While the engine
and radiator are hot, do not loosen or remove
the coolant reservoir cap or coolant inlet cap.
(The coolant inlet cap is located under the
engine cover.)
High temperature steam or coolant could
spray out. ●
RC300: While the engine and radiators are
hot, do not loosen or remove the coolant res-
ervoir cap, coolant inlet cap, or intercooler
coolant reservoir cap.
High temperature steam or coolant could
spray out.
●
RC F: While the engine and radiator are hot,
do not loosen or remove the coolant reser-
voir cap.
High temperature steam or coolant could
spray out.

621Alphabetical index
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U)Emergency, in case of
If a warning buzzer sounds...........453
If a warning light turns on...............453
If a warning message
is displayed ....................................... 460
If the electronic key
does not operate properly ......... 518
If the engine will not start................. 516
If the vehicle battery is
discharged ......................................... 522
If you have a flat tire .............489, 502
If you think something
is wrong................................................ 451
If your vehicle becomes stuck .....532
If your vehicle has to be
stopped in an emergency ..........443
If your vehicle needs
to be towed ....................................... 444
If your vehicle overheats ................526
Engine ....................................................... 539
ACCESSORY mode..................... 208
Compartment......................................397
Engine switch .......................................207
Hood ........................................................393
How to start the engine ..................207
Identification number ...................... 538
If the engine will not start................. 516
Ignition switch (engine switch)....207
Overheating .........................................526 Engine coolant ...................................... 404
Capacity................................................. 544
Checking ............................................... 404
Preparing and checking
before winter ........................320, 320
Engine coolant temperature
gauge ..................................................91, 96
Engine immobilizer system .................. 79
Engine oil ................................................. 400
Capacity.................................................540
Checking .............................................. 400
Preparing and checking
before winter ........................320, 320
Engine oil maintenance data ........... 403
Engine oil temperature gauge............96
Engine switch ..........................................207
Enhanced VSC ....................................... 312
EPS (Electric Power Steering) ......... 313
Warning light ....................................... 454
Event data recorder (EDR)................... 10
Expert mode ............................................ 316