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.
The dipsticks of engine oil and transmission oil looks similar, have upper and lower marks but the meaning of those marks and how they wre read differ.
Coolant can gain access to transmission through the transmission oil cooler. The oil cooler can leak internally causing the coolant and oil chambers to be linked.
Coolant getting into the engine lubrication system can cause damage to the engine. It is mostly caused by bad head gasket, bad radiator that has oil cooler integrated 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.