An engine has numerous moving parts, and where there is movement there is friction. Friction creates heat.
Motor oil is pumped throughout the engine block to provide some lubrication, but it isn’t enough to overcome all of this excess heat energy. As a result, parts of the engine become boiling hot as part of normal operations.
This is where the radiator system comes into play. The engine block must be kept relatively cool
to avoid serious problems like overheating and seizure. If the pistons cannot slide freely in their cylinders due to excessive friction, they will eventually snap and cause total engine failure. To prevent this from happening, a mixture of water and anti-freeze is pumped through chambers in the engine block to
absorb the excess heat and draw it away from vital areas.