Lexus GS450h Owner's Manual page 539

When adding coolant
■
Add coolant in accordance with the following procedure.
Remove caps A and B.
1
Add coolant through the inlet of cap A up to the "[GR-HV] B" line/"[AR/GR] B" line,
2
and then install cap A.
Add coolant through the inlet of cap B until it is full, and then install cap B.
3
GS300h only: When installing cap B, apply coolant to the O-ring on the end of cap B.
Cap A
1
Cap B
2
GS450h: "[GR-HV] B" line (Target fill line)
3
GS300h: "[AR/GR] B" line (Target fill line)
GS450h_300h_OM_OM30F92E_(EE)
7-2. Steps to take in an emergency
GS450h
539
GS300h
7