Answer: coolant

AnswerCrossword Clue
COOLANT

Freon, for one

COOLANT

Radiator additive

COOLANT

Car radiator need

COOLANT
Radiator fluid
COOLANT
Radiator fill
COOLANTNuclear reactor need
COOLANTCar-radiator contents
COOLANTNuclear reactor fluid
COOLANTAntifreeze, for one.
COOLANTHeat-reducing fluid
COOLANTEngine fluid
COOLANTCore fluid
COOLANTFreon, e.g.
COOLANTAntifreeze e.g.
COOLANTAir or water, perhaps