Air never hurt my old vehicle. How can it hurt my new one?

Radiators in the older vehicles were positioned higher than the engine. It used to be easy to just fill the radiator and run the vehicle until the thermostat opened and then top it off, put the radiator cap on and drive away. With newer vehicles, most manufacturers specify to purge the air out of the cooling system. 

If air gets trapped in the engine block or cylinder head(s) and it is run for any period of time it will cause "hot spots". This will damage head gaskets, the cylinder walls and the entire cooling system. Overheating and expensive repairs will be the end results.