Lexus RX 450h 2012 Owner's Manual page 660

NOTICE
When adding engine/power control unit coolant
■
Wait until the hybrid system has cooled down before adding engine/power control
unit coolant.
When adding coolant, do so slowly. Adding cool coolant to a hot hybrid system too
quickly can cause damage to the hybrid system.
To prevent damage to the cooling system
■
Observe the following precautions:
Avoid contaminating the coolant with foreign matter (such as sand or dust etc.).
●
Do not use commercially available coolant additives.
●
5-2. Steps to take in an emergency
5
659