Engine temperature looks simple on the dashboard, yet the system behind that gauge does complex work every second. A healthy radiator keeps combustion heat under control, protects expensive components ...

How hot does your engine run? Is it on the cool side? The hot side? Where should it be? How big of a radiator should you run? Antifreeze or water? Tap or distilled? Do you need a pressurized cooling ...

This is what the pros told me, including how long they stay warm after they’ve been switched off ...