Finding gems in my truck's workshop manual while making an webpage for all the technical specifications:
[T]he filter element should be renewed every 6000 miles (9600km) and it is advisable to renew the engine oil in the oil pan at the same time.
That's fantastic. "Change the filter, and maybe change the oil while you're at it."
God, the late 50s/early 60s were an time for vehicles...