[repp]

congrats on the world of compressed air.

the red dial above the gauge is to set the outlet air pressure from the two conections near it .

the black box in the second picture looks to be the air inlet filter, which I would open and clean it if aplicable.

as for the oil yes you should change it with a good oil recomended for air compressors.

and drain the water from the tank when you run it for any length of time.