cooling LEXUS RCF 2018 User Guide

398 6-3. Do-it-yourself maintenance
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U)
RC300
Fuse boxes (  P. 429)
Battery (  P. 408)
Engine oil level dipstick
(  P. 400)
Engine oil filler cap (  P. 402)
Engine coolant reservoir
(  P. 404)
Brake fluid reservoir (  P. 407) Washer fluid tank (  P. 411)
Electric cooling fans
Condenser (  P. 406)
Intercooler radiator (  P. 406)
Radiator (  P. 406)
Intercooler coolant reservoir
(  P. 404)1
2
3
4
5
6 7
8
9
10
11
12

3996-3. Do-it-yourself maintenance
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 6
Maintenance and care 
RC F
Fuse boxes (  P. 429)
Battery (  P. 408)
Engine oil level dipstick
(  P. 400)
Engine coolant reservoir
(  P. 404)
Engine oil filler cap (  P. 402) Brake fluid reservoir (  P. 407)
Washer fluid tank (  P. 411)
Electric cooling fans
Condenser (  P. 406)
Radiator (  P. 406)1
2
3
4
5 6
7
8
9
10

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

406 6-3. Do-it-yourself maintenance
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U)Check the radiator, condenser and interc ooler radiator and clear away any for-
eign objects.
If any of the above parts are extremely dirt y or you are not sure of their condition,
have your vehicle inspecte d by your Lexus dealer.WARNING ■
When the engine is hot (RC350/RC300)
Do not remove the engine coolant reservoir cap, intercooler coolant reservoir cap and
coolant inlet cap. (  P. 530)
The cooling system may be under pressure and may spray hot coolant if the cap is
removed, causing serious injuries, such as burns. ■
When the engine is hot (RC F)
Do not remove the engine coolant reservoir cap. (  P. 530)
The cooling system may be under pressure and may spray hot coolant if the cap is
removed, causing serious injuries, such as burns.
NOTICE ■
When adding 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 cool-
ing. 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.
Radiator, condenser and intercooler radiator (if equipped)
WARNING ■
When the engine is hot
Do not touch the radiator, condenser or inte rcooler as they may be hot and cause seri-
ous injuries, such as burns.

5257-2. Steps to take in an emergency
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 7
When trouble arises WARNING ■
Avoiding battery fires or explosions
Observe the following precautions to preven t accidentally igniting the flammable gas
that may be emitted from the battery: ●
Make sure each jumper cable is connected to the correct terminal and that it is not
unintentionally in contact with any other than the intended terminal.●
Do not allow the other end of the jumper cab le connected to the “+” terminal to come
into contact with any other parts or metal surfaces in the area, such as brackets or
unpainted metal. ●
Do not allow the + and - clamps of the jump er cables to come in to contact with each
other. ●
Do not smoke, use matches, cigarette lighters or allow open flame near the battery. ■
Battery precautions
The battery contains poisonous and corrosive acidic electrolyte, while related parts
contain lead and lead compounds. Observ e the following precautions when handling
the battery: ●
When working with the battery, always wear safety glasses and take care not to allow
any battery fluids (acid) to come into cont act with skin, clothing or the vehicle body.●
Do not lean over the battery. ●
In the event that battery fluid comes into contact with the skin or eyes, immediately
wash the affected area with water and seek medical attention.
Place a wet sponge or cloth over the affected area until medical attention can be
received. ●
Always wash your hands afte r handling the battery support, terminals, and other bat-
tery-related parts. ●
Do not allow childre n near the battery.
NOTICE ■
When handling jumper cables
When connecting the jumper cables, ensure that they do not become entangled in the
cooling fans or engine drive belt.

5277-2. Steps to take in an emergency
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 7
When trouble arises After the engine has cooled down suff iciently, inspect th e hoses and radiator
core (radiator) for any leaks.
Radiator
Cooling fans If a large amount of coolant leaks, immediately contact your Lexus dealer. 3
1
2
RC350/RC300 AWD 
RC300
RC F

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

5317-2. Steps to take in an emergency
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U) 7
When trouble arises NOTICE ■
When adding engine coolant
Add coolant slowly after the engine has cool ed down sufficiently. Adding cool coolant
to a hot engine too quickly can cause damage to the engine. ■
To prevent damage to the cooling system
Observe the following precautions: ●
Avoid contaminating the coolant with foreig n matter (such as sand or dust etc.).●
Do not use any coolant additive.

544 8-1. Specifications
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U)* : The fluid capacity is a reference quantity.
If replacement is necessary, contact your Lexus dealer.
■
Spark plugCooling system Capacity
* RC350/
RC300
AWD 10.0 qt. (9.5 L, 8.4 Imp. qt.)
RC300 
Gasoline engine
8.5 qt. (8.0 L, 7.0 Imp. qt.) 
Intercooler
3.3 qt. (3.1 L, 2.7 Imp. qt.)
RC F 12.2 qt. (11.5 L, 10.1 Imp. qt.)
Coolant type Use either of the following:
• “Toyota Super Long Life Coolant”
• Similar high-quality ethylene glycol-based non-sili-
cate, non-amine, non-nitrite, and non-borate coolant
with long-life hybrid organic acid technology
Do not use plain water alone.
Ignition system RC350/RC300
AWD RC300 RC F
Make DENSO
FK20HBR8 NGK
DILFR7K9G DENSO
FK20HBR-J8
Gap 0.031 in. (0.8 mm) 0.035 in. (0.9 mm) 0.031 in. (0.8 mm)
NOTICE ■
Iridium-tipped spark plugs
Use only iridium-tipped spark plugs. Do not adjust the spark plug gap.

619Alphabetical index
RC350_RC300 AWD_RC3 00_RC F_U(OM24748U)Cleaning......................................... 376, 381
Aluminum wheels .............................. 377
Exterior....................................................376
Interior ...................................................... 381
Seat belts ............................................... 382
Clock ......................................................... 355
Coat hooks..............................................358
Compass .................................................. 366
Condenser .............................................. 406
Console box ............................................ 351
Cooling system ..................................... 404
Engine overheating...........................526
Cruise control
Dynamic radar cruise control..... 268
Cup holders ............................................ 352
Current fuel consumption ....... 108, 122
Curtain shield airbags ........................... 40
Customizable features ....................... 569 Daytime running light system...........226
Defogger
Outside rear view mirrors ............338
Rear window........................................338
Windshield............................................338
Differential
Front differential .................................545
Rear differential................................... 546
Dimension ............................................... 536
Dinghy towing ....................................... 206
Display
Drive information...................... 108, 122
Dynamic radar cruise control .....268
LDA (Lane Departure Alert
with steering control) ................... 265
Multi-information display....... 103, 118
Warning message.............................460
Distance ...........................................108, 122
Do-it-yourself maintenance............... 391
Door courtesy lights
Location ................................................. 347
Door lock
Doors.........................................................145
Smart access system with
push-button start ..............................156
Wireless remote control..................140 D