A cool-down lap done at lowish speeds, with minimal braking, allowing the heat in the discs and pads to dissipate. 

Similarly for the engine, a gentle lap will allow the cooling system to lose some of the built-up heat from hard driving to cool down and the oil temp to drop.

They’ll still be hot when the car arrives back at its garage, but not excessively so.

Andrew Burden

The author Kiwi F1 Fan