Toyota LEXUS LS430 2005 Manual page 475

ENGINE
If the coolant level drops within a short time after replenishing,
there may be a leak in the system. Visually check the radiator,
hoses, engine coolant filler cap, radiator cap and drain cock
and water pump.
If you can find no leak, have your Lexus dealer test the cap
pressure and check for leaks in the cooling system.
CAUTION
To prevent burning yourself, do not remove the radiator
cap when the engine is hot.
456
Coolant type selection329.
Use of improper coolants may damage your engine cooling
system.
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. (Coolant with long−life hybrid organic
acid technology is a combination of low phosphates and
organic acids.)
For the U.S.A.—"Toyota Super Long Life Coolant" is a mixture
of 50% coolant and 50% deionized water. This coolant
provides protection down to about −35_C (−31_F).
For Canada—"Toyota Super Long Life Coolant" is a mixture of
55% coolant and 45% deionized water. This coolant provides
protection down to about −42_C (−44_F).
NOTICE
Do not use plain water alone.
Lexus recommends "Toyota Super Long Life Coolant", which
has been tested to ensure that it will not cause corrosion nor
result in malfunction of your engine coolant system with proper
usage. "Toyota Super Long Life Coolant" is formulated with
long−life hybrid organic acid technology and has been
specifically designed to avoid engine cooling system
malfunction on Lexus vehicles.
Please contact your Lexus dealer for further details.