Preventive and corrective maintenance on a used car that is just purchased is important since buyer might not have all details of maintenance history and sometimes, people sell their cars due to faults without full disclosure.
Coolant getting into the engine lubrication system can cause damage to the engine. It is mostly caused by a faulty head gasket, bad radiator that has oil cooler integrated in it or a bad engine oil cooler.
The serpentine belt drives accessories like water pump, alternator, AC compressor and power steering pump. When the belt cuts, these accessories stop functioning and the vehicle has a very limited time to run.